Good Day to you!
I've been asked to make some topic-wise list of problems I've solved. Even though I couldn't involve all problems, I've tried to involve at least "few" problems at each topic I thought up (I'm sorry if I forgot about something "easy"). I've alredy made such list once anyway I've tried to include more problems now — so here it is:
http://www.spoj.com/problems/ADAJOBS/
URI 2226 (5) //[NICE][NUMBERS][DP]
http://www.spoj.com/problems/SUB_PROB/en/
http://mirror.codeforces.com/contest/696/problem/D 8
http://www.spoj.com/problems/AHOCUR/ 5 //Aho-Corassic + DP
https://www.codechef.com/problems/LYRC (5) //Sample aho-brute-force
http://mirror.codeforces.com/problemset/problem/346/B //Proposed by bradyawn
6861 [LA] //CYK
UVA 10679 //Suffix Automat
http://www.spoj.com/problems/STRMATCH/ //Suffix Automat — trie might do too
http://www.spoj.com/problems/NSUBSTR2/ //Suffix Automaton
UVA 12519
http://www.spoj.com/problems/ARBITRAG/ (4) //Or Floyd-Warshall
http://www.spoj.com/problems/ADACYCLE/ [FW]
UVA 13295 (6) //[NICE][EFFICIENCY][IMPLEMENTATION]
http://mirror.codeforces.com/gym/101992/problem/H (4) //[VERY NICE][MAX]
http://mirror.codeforces.com/gym/100112 H
6151 — Beehives (4) //[NICE] //Search for shortest cycle
https://devskill.com/CodingProblems/ViewProblem/60
https://devskill.com/CodingProblems/ViewProblem/150
11312 UVA (3)
11392 UVA (4)
http://mirror.codeforces.com/contest/653/problem/E (6)
http://mirror.codeforces.com/contest/769/problem/C 5 //FL:ODD/**** | bfs+greed NICE
10968 UVA (3) //EASY + NICE (bfs withot <=2 nodes)
http://mirror.codeforces.com/contest/796/problem/D (3) //NICE+EASY ... print visited in bfs (not par)
10888 UVA (4) //VERY NICE — but not main technique ... ++ DP /or/ MCMF
http://mirror.codeforces.com/contest/821/problem/D (5) //VERY NICE — Consider only points not GRID
http://www.spoj.com/problems/DIGOKEYS/ (4) //Easy [Nice problem — weird statement]
http://www.spoj.com/problems/SPIKES/ (3) //Easy bfs (# of 's' * 2)
http://www.spoj.com/problems/MULTII/ (4) //VERY NICE: BFS over numbers (K*10+d)%N
http://www.spoj.com/problems/ADV04F1/ (5) //VERY NICE: [imple] ~ N^4*BigConstant
http://www.spoj.com/problems/INVESORT/ (5) //Big limit (really usefull :P)
http://mirror.codeforces.com/contest/59/problem/E (5) //[NICE][DOUBLE-STATES][SET]
http://mirror.codeforces.com/contest/877/problem/D (4) //[NICE] Add vector to # of states
4291 — Sculpture (6) //[NICE][PREPROCESS][NORMALIZE]
10977 UVA (3)
928 UVA (3)
13116 UVA (4)
314 UVA (3)
11487 UVA (4)
5622 LA (7)
11931 UVA (5)
http://www.spoj.com/problems/KNMOVE/ 3 //simple knights
http://www.spoj.com/problems/SERGRID/ 3 //almost classical
http://www.spoj.com/problems/NAKANJ/ 3 //Classical chess — KNIGHT
http://www.spoj.com/problems/PUCMM223/ (4) //NICE (but not many languages) — 2 moving [x][y]
http://www.spoj.com/problems/SPIRALGR/ (4) //NICE (not typical) [SIEVE]
http://www.spoj.com/problems/DCEPC706/ (4) //NICE — travelling outside
http://mirror.codeforces.com/contest/35/problem/C (3) //No obstacles [multiple starts]
https://devskill.com/CodingProblems/ViewProblem/394 (2) //Multiplication (or math)
http://mirror.codeforces.com/contest/66/problem/A (2) //Big + iffs + implementation
UVA — 10183
10106 — Product [UVA]
10523 — Very Easy !!! [UVA]
787 — Maximum Sub-sequence Product [UVA]
2871 — Rhyme Schemes [LA][BELL]
UVA — 10497
http://www.spoj.com/problems/MUL/en/
http://www.spoj.com/problems/ITRIX_E/
11115 — Uncle Jack
11448 — Who said crisis? [UVA]
http://www.spoj.com/problems/GCD2/
10083 — Division [UVA]
11830 — Contract Revision [UVA]
1230 — MODEX [UVA]
http://www.spoj.com/problems/NUMPLAY/
10519 — UVA
7651 — Pascal's Hyper-Pyramids [LA]
11344 — The Huge One [UVA]
10303 — How Many Trees? [UVA]
http://www.spoj.com/problems/FAST2/
495 — Fibonacci Freeze [UVA]
10023 — Square root [UVA]
http://www.spoj.com/problems/SKYLINE/
http://www.spoj.com/problems/NITT2/
11879 — Multiple of 17
http://www.spoj.com/problems/MINNUM/
10494 — If We Were a Child Again [UVA]
10013 — Super long sums [UVA]
10925 — Krakovia [UVA]
10814 — Simplifying Fractions [UVA]
619 — Numerically Speaking [UVA]
713 — Adding Reversed Numbers [UVA]
1226 — Numerical surprises [UVA]
623 — 500! [UVA]
http://mirror.codeforces.com/problemset/problem/18/D
http://www.spoj.com/problems/NUMTSN/
https://www.codechef.com/problems/FRJUMP
10220 — I Love Big Numbers ! [UVA]
https://www.hackerrank.com/contests/projecteuler/challenges/euler025
https://www.hackerrank.com/contests/projecteuler/challenges/euler020
11645 UVA 4
Gym — 100866A [ACM ICPC 2005–2006 NEERC Moscow Subregional Contest]
CSQUARE [SPOJ]
http://www.spoj.com/problems/PARCARD1/
10070 — Leap Year or Not Leap Year and .. [UVA]
http://www.spoj.com/problems/SOLDIERS/
12333 — Revenge of Fibonacci [UVA]
http://www.spoj.com/problems/NDIVPHI/
http://www.spoj.com/problems/IWGBS/ [UVA]
http://www.spoj.com/problems/POP3/ [Prime-Test]
http://www.spoj.com/problems/VGCD/
http://www.spoj.com/problems/NDIVPHI2/
12924 — Immortal Rabbits [UVA]
Count the Trees [UVA][10007]
10198 — Counting [UVA]
11375 UVA 3
http://www.spoj.com/problems/MINNUM/ 3 // BIG/9+!!(BIG%9)
10844 UVA 4 //Bell numbers + big (might be slightly slow!)
http://www.spoj.com/problems/NITT2/ 2 //Divisibility by two constants
http://www.spoj.com/problems/NUMPLAY/ (3) //With DP
http://www.spoj.com/problems/IWGBS/ (3) //Fibonacci 10^4
http://www.spoj.com/problems/PUCMM025/ (2) //Divisibility by 1 → 9
http://www.spoj.com/problems/CSQUARE/ (3) //Converse + Power
http://mirror.codeforces.com/contest/17/problem/D (5) //B^(N-1)*(B-1)%C [B/N are big]
https://mirror.codeforces.com/contest/1173/problem/C (4) //[NICE]
https://mirror.codeforces.com/contest/1201/problem/C (4) //[NICE][SIMPLE]
https://mirror.codeforces.com/contest/1183/problem/C (3) //[SIMPLE][NICE]
http://mirror.codeforces.com/gym/101628/problem/J (4) //[NICE][EASY]
http://mirror.codeforces.com/gym/101962 F //[NICE][FW]
http://mirror.codeforces.com/contest/920/problem/G (5) //[NICE][MATH][IE]
http://mirror.codeforces.com/contest/140/problem/C (4) //[NICE][GREEDY]
http://mirror.codeforces.com/contest/898/problem/E (4) //[NICE][SIMPLE][PREPROCESS]
http://mirror.codeforces.com/contest/888/problem/C (3) //Can be done without BS
http://mirror.codeforces.com/contest/68/problem/B (3) //[EASY][DOUBLE]
http://mirror.codeforces.com/contest/42/problem/A (2) //Or simple math
http://mirror.codeforces.com/contest/883/problem/I (4) //[NICE][SET][2Pointers]
http://mirror.codeforces.com/contest/51/problem/C (4) //[NICE][GREEDY-CHECK]
http://mirror.codeforces.com/contest/729/problem/C 3
http://mirror.codeforces.com/contest/714/problem/D 8
13150 (UVA) 4
http://mirror.codeforces.com/contest/749/problem/D 5
11692 (UVA) 4
11516 (UVA) 3
http://mirror.codeforces.com/contest/760/problem/B 3
http://mirror.codeforces.com/contest/675/problem/D 4 //dunno — solvable with treap
http://www.spoj.com/problems/NDS/ 4 //BS over LIS
http://www.spoj.com/problems/VECTAR4/ 3
http://mirror.codeforces.com/contest/767/problem/D 4 //NICE
http://mirror.codeforces.com/contest/627/problem/D (7) //with dp — NICE
http://mirror.codeforces.com/contest/779/problem/D (3) //NICE + EASY
http://www.spoj.com/problems/CNTINDX/ (4) //Map+BS === OK
13177 UVA (3) //BS over answer == OK
http://mirror.codeforces.com/contest/801/problem/C (3) //BS + SUM -EASY
http://mirror.codeforces.com/contest/803/problem/D (3) //BS by answer
http://mirror.codeforces.com/contest/807/problem/C (3) //Or math
http://mirror.codeforces.com/contest/818/problem/F (4) //NICE — Live VS Clique
http://mirror.codeforces.com/contest/845/problem/E (5) //VERY NICE — min(X,Y) .. add time, repeat
http://www.spoj.com/problems/MATHLOVE/ (2) //BS + Gaus (or otter ways)
http://www.spoj.com/problems/SABBIRGAME/ (3) //Binary search over answer ::max(0,ANS)
http://mirror.codeforces.com/contest/846/problem/D (4) //BS+Precalculation OR 2D-RMQ
http://www.spoj.com/problems/RPLC/ (3) //Classical
http://www.spoj.com/problems/TRIGALGE/ (2) //On doubles — simple function given
http://www.spoj.com/problems/ABA12E/ (4) //VERY NICE — BS on answer + 2Pointers
http://mirror.codeforces.com/contest/847/problem/E (4) //NICE: Back+Front OR Front+Back
http://www.spoj.com/problems/MAIN8_C/ (3) //Classical — simultion over array
http://www.spoj.com/problems/FUNFACT/ (4) //VERY NICE — Sterling Approximation
http://mirror.codeforces.com/contest/16/problem/C (3) //[or math][simple formula check]
http://mirror.codeforces.com/contest/21/problem/C (3) //[NICE][prefix-sum+lower_bound]
http://mirror.codeforces.com/contest/24/problem/E (5) //[doubles]
http://mirror.codeforces.com/contest/875/problem/E (6) //VERY NICE [BS][Keep possible places]
https://devskill.com/CodingProblems/ViewProblem/566 (2)
https://mirror.codeforces.com/gym/102006/problem/F (6) //[VERY NICE][DP]
http://mirror.codeforces.com/gym/101908/problem/I (3) //[EASY][XOR]
http://mirror.codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough
http://mirror.codeforces.com/contest/92/problem/B (2) //Bit addition/shifting (but big number)
http://mirror.codeforces.com/contest/907/problem/C (3) //Nice but ugly statement: sets
11659 UVA (4)
11535 UVA (4)
http://mirror.codeforces.com/contest/779/problem/E (5) //NICE + Parsing
http://www.spoj.com/problems/EC_CONB/ (1) //reverse numbers
http://mirror.codeforces.com/contest/769/problem/D (4) //freq + brute-force
http://www.spoj.com/problems/HAP01/ (2) //builtin_popcount
http://mirror.codeforces.com/contest/862/problem/C (3) //VERY NICE — Random works well
http://www.spoj.com/problems/KOMPICI/ (4) //NICE — Bitmask over digits
http://www.spoj.com/problems/ADACOINS/
http://www.spoj.com/problems/ADACHERY/
http://www.spoj.com/problems/ADAFUROW/
https://mirror.codeforces.com/contest/1194/problem/E (5) //[NICE][BRUTE]
https://www.spoj.com/problems/TTRGRAPH/ (4) //[NICE][GRAPH][CLIQUES]
https://www.spoj.com/problems/ILD18ACP/ (5) //[NICE][GRAPH][PATH]
http://mirror.codeforces.com/contest/914/problem/F (7) //[VERY NICE][POLYMUL-LIKE][BRUTE]
http://mirror.codeforces.com/contest/117/problem/C (5) //Finding 3cycles in directed graph [NICE]
http://mirror.codeforces.com/contest/754/problem/E 6
http://www.spoj.com/problems/UCBINTC/ 5 //polymul with bitset
http://mirror.codeforces.com/contest/33/problem/D (4) //VERY NICE [LCA works too]
http://mirror.codeforces.com/contest/918/problem/C (4) //Brute-force+Bitset (or...)
http://mirror.codeforces.com/contest/118/problem/E (4) //[NICE]//Orientation [+DFS]
315 — Network
796 — Critical Links
UVA 12363
Gym 100114J [2012-2013 ACM-ICPC, NEERC, Central Subregional Contest]
http://www.spoj.com/problems/ONBRIDGE/ [ONLINE][HARD][NICE][D&C]
http://mirror.codeforces.com/contest/732/problem/F 7
http://mirror.codeforces.com/contest/700/problem/C 7
http://www.spoj.com/problems/EC_P/ (3) //bridges ONLY
http://www.spoj.com/problems/SUBMERGE/ (3) //Direct articulation
http://www.spoj.com/problems/GRAFFDEF/ (5) //Bridge tree
http://mirror.codeforces.com/contest/1000/problem/E // Sugested by Warawreh
https://www.spoj.com/problems/YOSEQ/ (3) //[NICE][OBSERVATION]
UVA 13296 (5) //[NICE][RECURSION]
http://mirror.codeforces.com/gym/100112 (7) [L] //[PRECISION]
http://mirror.codeforces.com/gym/101806/problem/X (6) //[VERY NICE][DFS][IFS][OBSERVATION]
8259 — High Score LA //[VERY NICE][TS works too] add only low number to minimum (NOT WORKING?)
http://mirror.codeforces.com/contest/922/problem/B (2) //Test all pairs — observe 3rd
http://mirror.codeforces.com/contest/919/problem/B (1) //Simply simulate
http://mirror.codeforces.com/contest/146/problem/B (2) //Test all bigger numbers
http://mirror.codeforces.com/contest/911/problem/B (1)
7692 — Square Deal (4) //Permutations+Swap
http://mirror.codeforces.com/contest/907/problem/A (2) //try all triples 0→ 200
http://mirror.codeforces.com/contest/124/problem/B (3) //next-permutation
http://mirror.codeforces.com/contest/910/problem/C (3) //Next-permutation
http://mirror.codeforces.com/contest/898/problem/B (2) //Try all possibilities
6160 — Countdown (5) //[NICE][DFS][EFFICIENT?]
http://mirror.codeforces.com/contest/122/problem/C (3) //Just around 2^10 lucky [RECURSION]
7899 — Mr. Panda and Strips (4) //Weak test-cases
7671 What a Beautiful Lake (2) //Try up/down from every node
http://mirror.codeforces.com/contest/110/problem/A (1) //4 or 7
http://mirror.codeforces.com/contest/106/problem/B (2) //Cycles -_-
http://mirror.codeforces.com/contest/895/problem/A (2) //All segments [in circle]
http://mirror.codeforces.com/contest/893/problem/B (2) //Try each divisor
http://mirror.codeforces.com/contest/894/problem/A (1) //3-cycles
http://mirror.codeforces.com/contest/892/problem/C (3) //Try to find "1" ASAP
http://mirror.codeforces.com/contest/102/problem/A (2) //Iterate over all triples
http://mirror.codeforces.com/contest/96/problem/B (2) //Check all
http://mirror.codeforces.com/contest/94/problem/B (1) //3cycles
http://mirror.codeforces.com/contest/887/problem/B (3) //Test all numbers
http://mirror.codeforces.com/gym/101597/problem/A (4) //[MATH][MODULO][SIMULATION]
http://mirror.codeforces.com/contest/68/problem/C (5) //[VERY NICE][RECURSION][MAX COST MIN FLOW]
http://mirror.codeforces.com/contest/68/problem/A (1) //Simple simulation
http://mirror.codeforces.com/contest/66/problem/B (2) //Test always whole platform
http://mirror.codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough
http://mirror.codeforces.com/contest/46/problem/C (2) //[2pointers][N^2 works too]
http://mirror.codeforces.com/contest/47/problem/D (4) //[Implementation][DFS]
http://mirror.codeforces.com/contest/51/problem/D (4) //Check all/check without 1s/2nd
http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_b (2)
http://mirror.codeforces.com/contest/53/problem/B (3) //at most 60 possibilities
http://mirror.codeforces.com/contest/55/problem/B (3) //Try all permutations & possibilities [NICE]
http://mirror.codeforces.com/contest/877/problem/B (3) //NICE [N^2][PrefixSum]
LA 6623 — Battle for Silver (3) //4 for-cycles inside ~ K4 search
UVA 12169 (2)
http://mirror.codeforces.com/contest/725/problem/C 4
http://mirror.codeforces.com/contest/725/problem/E 6
http://mirror.codeforces.com/contest/724/problem/B 3
11961 UVA (2)
11898 UVA (4)
11659 UVA (4)
http://mirror.codeforces.com/contest/753/problem/C 7
11699 UVA (4)
11548 UVA (3)
11471 UVA (5) //With dynamic programming
http://mirror.codeforces.com/contest/698/problem/D 8 //with geometry
http://mirror.codeforces.com/gym/101840 F //[NICE][BS][DISTANCE]
11206 UVA (6) //4^20 (but somehow passes)
11214 UVA (6) //Úvaha + pruning
11127 UVA (4) //Simple dfs [just realize you can do so]
http://www.spoj.com/problems/BOKAM143SOU/ (3) //just implement for-cycles
http://www.spoj.com/problems/BLOPER/ (4) dfs with little pruning
13173 UVA (3) //just brute-force + branching
http://mirror.codeforces.com/contest/799/problem/D (4) //VERY NICE [only top 34 needed] — trick with 2 [~20]
10890 UVA (4) //Simple brute-force times out, but with simple pruning AC (answer detection
http://mirror.codeforces.com/contest/813/problem/B (3) //All*All (BF) care for overflow! NICE & EASY
http://mirror.codeforces.com/contest/817/problem/C (3) //Check S+Constant (NICE!)
10732 UVA (2) //Brute-force passes .. just don't trust them O(N^2)
10748 UVA (5) //VERY Nice (knights have K^2 moves not 8^K)
http://mirror.codeforces.com/contest/818/problem/D (4) //NICE for each 'A' check all remaining (max SQRT)
http://mirror.codeforces.com/contest/834/problem/E (5) //NICE — hard to imple: all 11122...999 OK
http://www.spoj.com/problems/JHAGIRLS/ (4) //Efficient — or store output in array
http://mirror.codeforces.com/contest/846/problem/B (3) //Brute-force
http://www.spoj.com/problems/ALONE/ (4) //Generate everything <10^15 [NICE]
http://mirror.codeforces.com/contest/861/problem/B (3) //Check all floor-sizes
http://www.spoj.com/problems/RRANGE/ (3) //Compare all queries agains all updates + GAUSS
http://mirror.codeforces.com/contest/598/problem/B (3) //Treap works too ;-)
http://www.spoj.com/problems/AMR10I/ (4) //Can be solved with brute-force with dp
http://mirror.codeforces.com/contest/868/problem/C (4) //Brute-force (fixet at most 6 each bits)
http://mirror.codeforces.com/contest/868/problem/D (5) //NICE: Maximal K is low (I assumed 15)
http://mirror.codeforces.com/contest/31/problem/C (2) //LOW-Constaints: N^2
http://mirror.codeforces.com/contest/32/problem/D (3) //Simply try all possibilities
http://mirror.codeforces.com/contest/876/problem/C (3) //Try N and ~100 lower
http://mirror.codeforces.com/contest/44/problem/B (2) //N^2 works fine
https://mirror.codeforces.com/gym/101991/problem/A (5) //[VERY NICE][FW]
http://mirror.codeforces.com/gym/101864 D //[NICE][SACK][ARPA][HLD]
http://mirror.codeforces.com/gym/101840 E //NICE
DCP-176: Motku2 [DevSkills]
http://mirror.codeforces.com/contest/715/problem/C 9
http://mirror.codeforces.com/contest/741/problem/D 8
13164 UVA (7)
http://mirror.codeforces.com/contest/752/problem/F 5
http://mirror.codeforces.com/contest/766/problem/E 6
http://mirror.codeforces.com/contest/833/problem/D 7 //Very nice — hard (thinking + imple) + FW
http://www.spoj.com/problems/HOLI/ (4) //VERY NICE: 2*Distances from centroids
https://mirror.codeforces.com/gym/102006/problem/K (6) //[VERY NICE][THEOREM][OBSERVATION]
http://mirror.codeforces.com/contest/741/problem/C 6
11331 UVA (4)
http://www.spoj.com/problems/ADATEAMS/
http://www.spoj.com/problems/ADASUM/
https://mirror.codeforces.com/contest/1173/problem/D (4) //[VERY NICE][DFS][FACTORIAL]
https://atcoder.jp/contests/abc136/tasks/abc136_f (5) //[VERY NICE][IE][POWER][FENWICK]
https://mirror.codeforces.com/contest/1178/problem/C (3) //[NICE][EASY][POWER]
https://mirror.codeforces.com/gym/101972/problem/J (4) //[NICE][THEOREM][COMB-NUMBERS]
https://mirror.codeforces.com/gym/101972/problem/I (5) //[NICE][SHORT][COMB-NUMBERS]
http://mirror.codeforces.com/gym/101628/problem/G (5) //[NICE][COMB-NUMBERS]
http://mirror.codeforces.com/gym/101864 E //Combination number, power
http://mirror.codeforces.com/gym/101879/problem/E (2) //Power of 2
http://mirror.codeforces.com/gym/101873 (5) //Necklace (mby burnside)
http://mirror.codeforces.com/gym/101808/problem/F (3) //[EASY]][FACTORIAL]
http://mirror.codeforces.com/problemset/problem/364/A (4) //[NICE][STL-or-sorting][IF]
http://mirror.codeforces.com/contest/145/problem/D (7) //[VERY NICE][SET][OBSERVATION][BS][BIG]
http://mirror.codeforces.com/contest/909/problem/B (3)
http://mirror.codeforces.com/contest/131/problem/C (3) //[EASY][BRUTE-FORCE][COMB-NUMBERS]
http://mirror.codeforces.com/contest/131/problem/B (2) //[EASY]
http://mirror.codeforces.com/contest/129/problem/E (5) //[NICE][COMB-NUMBERS]//Observe
http://mirror.codeforces.com/contest/111/problem/D (5) //[COMB-NUMBERS][POWER][VERY NICE][DP]
http://mirror.codeforces.com/contest/895/problem/D (4) //[COMB-NUMBERS][OPTI]
http://mirror.codeforces.com/contest/893/problem/E (5) //[COMB-NUMBERS][NUMBER-THEORY]
http://mirror.codeforces.com/contest/894/problem/B (3) //try without last row
http://mirror.codeforces.com/contest/890/problem/E (6) //Permutations
http://mirror.codeforces.com/contest/52/problem/B (4) //[NICE][PREPROCESS][ROTATION]
3917 //Grid tiling [fancy approximation fomula]
http://mirror.codeforces.com/contest/760/problem/F
https://devskill.com/CodingProblems/ViewProblem/61
https://devskill.com/CodingProblems/ViewProblem/255
UVA 10918
UVA 12576
UVA 1118 //Parity
http://www.spoj.com/problems/HLP_RAMS/ //Comb parity
Project Euler #78: Coin partitions //Partition function
http://www.spoj.com/problems/MAIN75/ //DP #of trees
12001 UVA (3)
12034 UVA (4)
11719 UVA (5)
11798 UVA (5)
11282 UVA (4) //dearrangement
11174 UVA (4)
http://mirror.codeforces.com/contest/666/problem/C 7
http://www.spoj.com/problems/JOKER1/ 3 prod(Ai-i)
http://www.spoj.com/problems/ANTP/ //4
http://mirror.codeforces.com/contest/645/problem/E (5) //formula: A[i]=Sum(A)+1
http://www.spoj.com/problems/SPCE/ (5) // N^{K-2}*Prod(comp_size)
http://mirror.codeforces.com/contest/785/problem/D (5) // F'(' C"(+)-1","("
13184 UVA (3)
http://mirror.codeforces.com/contest/816/problem/D (5) // Observation
13214 (4) //OEIS? : C(N+M-2,N-1)
http://mirror.codeforces.com/contest/844/problem/B (2) //Easy — pro prvaky
http://www.spoj.com/problems/JOSWAP/ (3) //Frequence array
http://www.spoj.com/problems/UCV2013E/ (4) //NICE&EASY: Choose steps to direction
http://www.spoj.com/problems/PARCARD1/ (4) //Partition function (raw)
http://www.spoj.com/problems/GOODB/ (2) //Easy (NICE): Choose [order]
http://www.spoj.com/problems/LOOPEXP/ (4) //A000254/N!
http://www.spoj.com/problems/DTPOLY/ (5) //DP might work too
http://www.spoj.com/problems/DTPOLY2/ (7) //Harder version of above (NICE but hell)
http://www.spoj.com/problems/HC12/ (3) //NICE — Sort + C(i,K-1)*A[i]
http://www.spoj.com/problems/STONE2/ (4) //NICE — Mostly DP [INVERSION][FACTORIAL]
http://www.spoj.com/problems/MAIN8_D/ (5) //NICE — Suffixes/Prefixes (same add 2^i)
http://www.spoj.com/problems/ITRIX_E/ (4) //VERY NICE — #Nonattacking 2-queens
http://www.spoj.com/problems/MAXSUB/ (3) //NICE — Subsets made of zeroes
http://www.spoj.com/problems/SKYLINE/ (3) //Catalan numbers [weird modulo — care]
http://mirror.codeforces.com/contest/26/problem/D (5) //Division of two combintion numbers [NI:/]
http://mirror.codeforces.com/contest/872/problem/E (6) // Prod:Sum(C(DistLines,CompSize))
https://mirror.codeforces.com/contest/1174/problem/C (4) //[VERY NICE][SIEVE]
https://mirror.codeforces.com/contest/1173/problem/B (3) //[VERY NICE][MATH]
https://mirror.codeforces.com/contest/1202/problem/D (4) //[NICE][MATH][GREEDY]
https://mirror.codeforces.com/contest/1199/problem/E (5) //[VERY NICE!][OBSERVATION][DFS]
https://mirror.codeforces.com/contest/1180/problem/D (5) //[VERY NICE][OVSERVATION]
https://mirror.codeforces.com/contest/1178/problem/D (4) //[VERY NICE][OBSERVATION][NUMBER THEORY]
https://mirror.codeforces.com/contest/1187/problem/C (4) //[NICE][IMPLEMENTATION]
http://mirror.codeforces.com/contest/922/problem/F (6) //[NICE][MATH][GREEDY]
http://mirror.codeforces.com/contest/916/problem/C (3) //Graph construction
http://mirror.codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)
http://mirror.codeforces.com/contest/909/problem/F (6) //[VERY NICE][BITS]
http://mirror.codeforces.com/contest/141/problem/C (4) //[NICE][BRUTE-FORCE]
http://mirror.codeforces.com/contest/907/problem/D (5) //[VERY NICE][RANDOM]
http://mirror.codeforces.com/contest/124/problem/C (3) //[NICE][SIEVE]
http://mirror.codeforces.com/contest/125/problem/C (4) //[NICE][C(N,2)]
http://mirror.codeforces.com/contest/902/problem/C (4) //[NICE]//Tree isomorphism
http://mirror.codeforces.com/contest/112/problem/C (3) //[GREEDY]//Max + 1s
http://mirror.codeforces.com/contest/110/problem/B (2) //Easy modulo
http://mirror.codeforces.com/contest/894/problem/C (3) //[VERY NICE] //AiAiGCD
http://mirror.codeforces.com/contest/97/problem/B (4) //NICE — Walls in middles [D&C]
http://mirror.codeforces.com/contest/85/problem/A (3) //MODULO / SHIFT
http://mirror.codeforces.com/contest/81/problem/D (3) //NICE — MAX(N/2) — even/odd
http://mirror.codeforces.com/contest/63/problem/D (3) //NICE[GO BY LINES][4 WAYS B/D ODD/EVEN]
http://mirror.codeforces.com/contest/42/problem/C (4) //Constructive works too but random is fine :)
http://mirror.codeforces.com/contest/43/problem/D (3) //NICE — Easy to see [implementation]
http://mirror.codeforces.com/contest/53/problem/C (2) //EASY [B/E Alternate]
http://mirror.codeforces.com/contest/877/problem/C (3) //NICE 3*Alternative
http://mirror.codeforces.com/contest/802/problem/H (6) //We can do "N+k" by adding a letter p+k*x+u+xx
http://mirror.codeforces.com/contest/12/problem/E (5) //g[i][j]=1+(i+j)%(N-1) [+/-]
http://mirror.codeforces.com/contest/22/problem/C (4) //Start and then clique without v (+ random)
http://mirror.codeforces.com/contest/26/problem/C (5) //make Even*Even: do by 2*2 fields
http://mirror.codeforces.com/contest/41/problem/E (4) //[NICE][CN/2,N/2]
http://mirror.codeforces.com/contest/78/problem/B (2) //NICE — last 3 and then rest in modulo
http://mirror.codeforces.com/contest/109/problem/D (5) //[NICE][BACK-POINTERS][SIMULATION][SORT]
http://www.spoj.com/problems/ADASEA/
https://mirror.codeforces.com/contest/1176/problem/E (4) //[NICE][CONSTRUCTIVE][TREE][TOPO]
https://mirror.codeforces.com/contest/1186/problem/F (5) //[NICE][GREEDY][CONSTRUCTIVE]
https://mirror.codeforces.com/contest/1189/problem/D2 (5) //[NICE][CONSTRUCTIVE]
https://atcoder.jp/contests/agc035/tasks/agc035_b (4) //[NICE][DIRECTION]
https://www.spoj.com/problems/CHUNK2/ (3) //[DFS][PRIMES]
https://mirror.codeforces.com/gym/101981 K //[VERY NICE][IMPLE][TREE][SIMULATION]
https://www.urionlinejudge.com.br/judge/en/problems/view/1621 (4) //[TREE][IMPLE]
https://www.urionlinejudge.com.br/judge/en/problems/view/1610 (3) //[CYCLE]
https://www.urionlinejudge.com.br/judge/en/problems/view/2911 (4) //[NICE][RULES][SIMPLE]
https://mirror.codeforces.com/gym/102001/problem/K (4) //[VERY NICE]
https://mirror.codeforces.com/gym/101972/problem/B (6) //[VERY NICE][TREE][STL]
https://toph.co/p/incompatible-crops (2)
http://mirror.codeforces.com/gym/100112 K //[NICE][BS][COLORING]
http://mirror.codeforces.com/gym/101962 D //[NICE] //Bitset shall work too
4286 — Equilibrium Mobile LA //[VERY NICE][OBSERVATION][TREE][DP]
http://mirror.codeforces.com/gym/101801 (4) [H] //[TREE][DP] //More dfss
https://www.urionlinejudge.com.br/judge/en/problems/view/2732 (3) //Easy flood
http://mirror.codeforces.com/contest/920/problem/E (5) //[NICE][DFS][SET] //Or clever random
http://mirror.codeforces.com/contest/915/problem/D (4) //[VERY NICE][CYCLES DETECTION (ORIENTED)]
http://www.spoj.com/problems/CTTC/ (3) //[EASY][GRAPH-RECONSTRUCTION]
7951 — Islands (3) //[NICE]Flood-Fill
http://mirror.codeforces.com/contest/901/problem/D (7) //Observations / Tree reduction
http://mirror.codeforces.com/contest/902/problem/B (3) //No dfs needed
http://mirror.codeforces.com/gym/101630 {C}(4) //[NICE][SCC]
http://mirror.codeforces.com/gym/101620 {J}(4) //DFS + multiples of divisors
http://mirror.codeforces.com/contest/120/problem/F (3) //Width of tree
7606 — Percolation (3) //Dfs on grid [EASY]
http://mirror.codeforces.com/contest/116/problem/C (2) //[DEPTH]
8080 — Christmas Tree (3) //[SIMPLE][NICE]
6584 — Escape (8) //[VERY VERY VERY NICE][COMPRESSION][MERGING] //Hard but I recommend this one!!
6590 Digraphs (4) //[VERY NICE][CYCLES][DP][IDEA]
http://mirror.codeforces.com/contest/893/problem/C (3) //Minimum from each connected component
http://mirror.codeforces.com/contest/884/problem/C (3) //[EASY][PERMUTATIONS][SORTING]
http://mirror.codeforces.com/contest/883/problem/G (4) //Greedy picking
http://mirror.codeforces.com/contest/60/problem/B (3) //3D Flood-Fill [NICE][EASY]
http://mirror.codeforces.com/contest/60/problem/C (4) //[VERY NICE][BF]//Not many real possibilities
https://devskill.com/CodingProblems/ViewProblem/3
https://devskill.com/CodingProblems/ViewProblem/17
https://devskill.com/CodingProblems/ViewProblem/118 //Kind-of
657 — The die is cast [UVA]
12186 UVA (3)
http://mirror.codeforces.com/contest/734/problem/E (5)
http://mirror.codeforces.com/contest/727/problem/A (3)
http://mirror.codeforces.com/contest/723/problem/E (6)
http://mirror.codeforces.com/contest/709/problem/E (6)
http://mirror.codeforces.com/contest/710/problem/E (4)
http://mirror.codeforces.com/contest/758/problem/E (8)
11323 UVA (5)
http://mirror.codeforces.com/contest/760/problem/B (3)
http://mirror.codeforces.com/contest/761/problem/E (6)
http://mirror.codeforces.com/contest/638/problem/B (3) //connect cons. letters
http://mirror.codeforces.com/contest/638/problem/C (4) //greedy idea — easy
http://mirror.codeforces.com/contest/638/problem/D (5) //spec-DAG articulatin
http://mirror.codeforces.com/contest/767/problem/C (4)
http://mirror.codeforces.com/contest/781/problem/C (5)
http://mirror.codeforces.com/contest/794/problem/D (5) //NICE! Right done dfs
http://mirror.codeforces.com/contest/802/problem/K (5) //Slightly DP-like (NICE) TREE
http://mirror.codeforces.com/contest/813/problem/C (3) //Simply 2 DFS: NICE + EASY
http://mirror.codeforces.com/contest/841/problem/D (4) //DFS while tracking "next"
http://mirror.codeforces.com/contest/845/problem/G (5) //Keep track of cycles
http://mirror.codeforces.com/contest/844/problem/E (5) //Post-Order → line, Connect i → N-2: star
http://www.spoj.com/problems/CAC/ (5) //VERY NICE! — Find all cycles in cactus
http://mirror.codeforces.com/contest/849/problem/C (3) //State search by gauss
http://mirror.codeforces.com/contest/846/problem/E (5) //NICE: DFS + some overflow logic
http://www.spoj.com/problems/KOZE/ (3) //NICE: Floods
http://www.spoj.com/problems/RIOI_2_3/ (4) //DFS /OR/ BFS /OR/ DSU [NICE][EASY][BF]
http://www.spoj.com/problems/MAKEMAZE/ (3) //EASY — Simple dfs on grid
http://mirror.codeforces.com/contest/861/problem/F (5) //VERY NICE: Modify dfs tree so it remains connected
http://www.spoj.com/problems/GHOSTS/ (3) //NICE — must remain dag after each QR
http://www.spoj.com/problems/AMR10J/ (5) //VERY NICE! — DFS+DP [DAG with cycles]
http://mirror.codeforces.com/contest/24/problem/A (2)//NICE [DFS-ON-CYCLE]
http://mirror.codeforces.com/contest/29/problem/C (3) //Find begining/end of line (graph)
http://mirror.codeforces.com/contest/29/problem/D (4) //Tree [implementation][simulation]
https://devskill.com/CodingProblems/ViewProblem/564 (2) //[OBSERVATION]
http://www.spoj.com/problems/PR003004/ (4) //Simple digits count
http://mirror.codeforces.com/contest/770/problem/B (3) //max num max digsum
http://www.spoj.com/problems/ADATRIP/
https://www.urionlinejudge.com.br/judge/en/problems/view/1655 (4) //[EASY][PROBABILITY]
https://www.urionlinejudge.com.br/judge/en/problems/view/2910 (4) //[TREE]
http://mirror.codeforces.com/gym/101628/problem/f (4)
http://mirror.codeforces.com/gym/100112 E //[NICE][BS][GEOMETRY]
http://mirror.codeforces.com/gym/101845/problem/J (5) //[NICE][OBSERVATION][TWICE]
http://mirror.codeforces.com/gym/101801 K //[NICE][MULTIPLE NODES]
http://mirror.codeforces.com/gym/101879/problem/F (8) //[NICE][BRIDGE]
http://mirror.codeforces.com/gym/101666 D //[NICE]
http://mirror.codeforces.com/contest/144/problem/D (4) //[VERY NICE][IFS]
http://www.spoj.com/problems/ADRABR/ (3) //Classical dijkstra — bad statement
http://mirror.codeforces.com/contest/141/problem/D (5) //[NICE]Many Conditions
6583 Subway (5) //[NICE]//Not exactly dijkstra by slightly similar [IMPLEMENTATION]
3850 [LA]
Gym 100625D [2013 Benelux Algorithm Programming Contest (BAPC 13)]
UVA 12950
Gym 100753A [2015 German Collegiate Programming Contest (GCPC 15) + POI 10-T3]
UVA 13030
UVA 1027
UVA 11377
http://mirror.codeforces.com/problemset/problem/843/D
11813 UVA
Gym 101242B [2016 ACM-ICPC World Finals] //+DP
Gym 100923B [2015 ACM National Contest Romania — Round 1]
UVA 11833
http://www.spoj.com/problems/EZDIJKST/en/
LightOJ 1019
UVA 13010 //+TS
2819 [LA]
UVA 12144
http://mirror.codeforces.com/contest/716/problem/D 7
12047 UVA 4
11514 UVA 4
http://mirror.codeforces.com/contest/757/problem/F 7
11338 UVA (4)
11374 UVA (4)
11097 UVA (4) //Divide to N*1000 nodes and go!
13172 UVA (5) //6*DJ per query + permutations
10816 UVA (4) //Easy Linear-Search by answer + DJ with path
http://mirror.codeforces.com/contest/827/problem/F 7 //Very nice — Even&Odd
http://www.spoj.com/problems/DELIVER/ (5) //Normalize coordinates + Optimalize
http://www.spoj.com/problems/CCHESS/ (4) //Dijkstra as knight
https://mirror.codeforces.com/contest/1175/problem/F (7) //[VERY NICE][HASH][RANDOMISATION]
https://mirror.codeforces.com/contest/1181/problem/E2 (7) //[VERY NICE][SORTING][ST]
https://mirror.codeforces.com/contest/1181/problem/E1 (5) //[VERY NICE][OBSERVATION][SORTING]
https://mirror.codeforces.com/gym/102058/problem/G (7) //[VERY NICE][BS][PRIORITY_Q]
http://mirror.codeforces.com/gym/101845/problem/L (6) //[VERY NICE][INDUCTION]
http://mirror.codeforces.com/gym/101801 J //[NICE][TRIE][RMQ]
8257 — Factor-Free Tree LA //[VERY VERY NICE][PRIMES][FACTOR]
https://www.urionlinejudge.com.br/judge/en/problems/view/1683 (4) //RAW histogram
http://mirror.codeforces.com/contest/817/problem/D (5) //Very nice NlogN
http://www.spoj.com/problems/DYNACON2/ (8) //Lesser hell — offline Nlog(N) /or/ NlogN^2
http://mirror.codeforces.com/contest/876/problem/F (5) //VERY NICE — Find greatest + next/back functions
https://mirror.codeforces.com/contest/1176/problem/D (4) //[NICE][GREEDY][SORTING]
https://atcoder.jp/contests/abc136/tasks/abc136_e (5) //[NICE][GREEDY][DIVISORS]
https://mirror.codeforces.com/contest/1183/problem/F (5) //[VERY NICE][SORTING][OBSERVATION][BF]
https://www.spoj.com/problems/KPOWERSUM/ (4) //[FACTORISATION]
http://mirror.codeforces.com/gym/101992/problem/D (5) //[VERY NICE][IE][NUMBER THEORY]
http://mirror.codeforces.com/gym/101982 B //[FACTORISATION][GCD][SIEVE]
http://mirror.codeforces.com/gym/101864 G //[VERY NICE][FACTORISATION][GCD]
http://mirror.codeforces.com/gym/101840 D //[EVENTS][NICE]
http://mirror.codeforces.com/gym/101741/problem/F (6) //[NICE][PROBABILITY][GCD]
http://www.spoj.com/problems/FRNDAM/ (3) //Simply find sum of all divisors (low constraints)
http://mirror.codeforces.com/contest/920/problem/F (5) //[NICE][FAST FALL][SET][DIVISORS]
7726 A Simple Math Problem (4) //TLE if naive (consider only divisors)
http://mirror.codeforces.com/contest/112/problem/D (4) //[NICE] Last-position [FACTOR]
http://mirror.codeforces.com/contest/75/problem/C (3) //[NICE][BS]
LightOJ 1068
LightOJ 1134
Project Euler #95: Amicable chains
NAJ0001 — Divisible Number Sum [SPOJ]
http://www.spoj.com/problems/LCMSUM/
https://www.hackerrank.com/contests/101hack38/challenges/easy-gcd-1/problem
UVA 13085
http://www.spoj.com/problems/CDRSANJ/
http://www.spoj.com/problems/DIVSEQ/
UVA 12154
UVA 13058
http://www.spoj.com/problems/EC_DIVS/
https://www.codechef.com/problems/CHEFKEY
http://mirror.codeforces.com/problemset/problem/671/C
Gym 101411G [2009-2010 ACM-ICPC, NEERC, Western Subregional Contest]
http://mirror.codeforces.com/problemset/problem/831/F
http://mirror.codeforces.com/problemset/problem/839/D
12934 — Factorial Division [UVA]
UVA 10880
http://www.spoj.com/problems/PSTR/
http://mirror.codeforces.com/problemset/problem/27/E
[LA] 3014
UVA 12843
https://www.urionlinejudge.com.br/judge/en/problems/view/1164
http://mirror.codeforces.com/problemset/problem/803/F
10892 — LCM Cardinality
http://www.spoj.com/problems/GCDEX/
http://www.spoj.com/problems/INVDIV/
13083 — Yet another GCDSUM //ll
http://www.spoj.com/problems/IITKWPCF/ //ll
UVA 13185
UVA 13194
UVA 11388
http://www.spoj.com/problems/SAS002/
12425 — Best Friend
http://mirror.codeforces.com/problemset/problem/703/E
https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy/
UVA 10830 //SUM
http://www.spoj.com/problems/DIVSUM/en/ //SUM
http://www.spoj.com/problems/AFS/ //SUM
UVA 11526 //SUM
http://www.spoj.com/problems/ADAZOO/
http://www.spoj.com/problems/ADASEQEN/
http://www.spoj.com/problems/ADAMOLD/
http://www.spoj.com/problems/ADASALE/
https://mirror.codeforces.com/contest/1203/problem/F2 (6) //[VERY NICE][GREEDY][SORTING][CASES]
https://mirror.codeforces.com/contest/1176/problem/F (5) //[NICE][IMPLE][SORTING]
https://mirror.codeforces.com/contest/1200/problem/F (6) //[NICE][DFS][GRAPH][LCM][MATH]
https://mirror.codeforces.com/contest/1201/problem/D (5) //[NICE][DP][IMPLE][CASES]
https://www.spoj.com/problems/THECODE/ (4) //[BITMASK]
https://mirror.codeforces.com/contest/1199/problem/F (5) //[NICE][DIMENSIONS]
https://mirror.codeforces.com/contest/1183/problem/H (4) //[NICE][SUBSEQUENCE][NEXT]
https://mirror.codeforces.com/contest/1183/problem/E (4) //[NICE][SUBSEQUENCE][NEXT]
https://mirror.codeforces.com/contest/1178/problem/F2 (7) //[VERY NICE][OBSERVATION]
https://mirror.codeforces.com/contest/1178/problem/F1 (5) //[NICE][MATH][REDUCTION]
https://mirror.codeforces.com/contest/1178/problem/B (3) //[EASY]Not even real DP
https://mirror.codeforces.com/contest/1195/problem/C (3) //[EASY]
https://mirror.codeforces.com/contest/1189/problem/F (6) //[VERY NICE][OBSERVATION]
https://atcoder.jp/contests/agc035/tasks/agc035_d (5) //[VERY NICE][BIT][IDEA]
https://www.spoj.com/problems/PLOVER/ (4) //[NICE][DIGITS]
https://www.spoj.com/problems/NICESEQ/ (4) //[DIGITS][POSSIBLY FASTER]
https://mirror.codeforces.com/gym/101981 L //[NICE]
https://www.spoj.com/problems/RANDMOD/ (4) //[OBSERVATION][SEQUENCE]
https://www.urionlinejudge.com.br/judge/en/problems/view/1592 (4) //[GRAPH]
https://www.urionlinejudge.com.br/judge/en/problems/view/2824 (4) //Classical
https://mirror.codeforces.com/gym/102006/problem/D (4) //[NICE][OBSERVATION]
https://mirror.codeforces.com/gym/102021 K
https://mirror.codeforces.com/gym/102058/problem/D (5) //[NICE][DOMINATION]
UVA 13294 (4) //[BIT]
http://mirror.codeforces.com/gym/101992/problem/A (6) //[BITS][OBSERVATION]
http://mirror.codeforces.com/gym/101628/problem/H (3) //[NICE][CLASSICAL][DAG]
http://mirror.codeforces.com/gym/101628/problem/A (3)
http://mirror.codeforces.com/gym/100112 J //[NICE][TREE]
http://mirror.codeforces.com/gym/101982 D //[VERY NICE][BITS] //Window
http://mirror.codeforces.com/gym/101982 C //Classical combinatorics
http://mirror.codeforces.com/gym/101845/problem/E (5)
https://www.codechef.com/problems/SPECTAC (5) //[NICE]
http://mirror.codeforces.com/gym/101801 [E]
http://mirror.codeforces.com/gym/101801 D //[VERY NICE][SEGMENT TREE][SORTING][NORMALIZE]
http://mirror.codeforces.com/gym/101873 J //[NICE][IMPLEMENTATION][STRING][SUBSUBSET]
http://mirror.codeforces.com/gym/101889 E
http://mirror.codeforces.com/gym/101808/problem/D (7) //[NICE][OPTIMISATION][EFFICIENCY]
http://mirror.codeforces.com/gym/101666 I
http://mirror.codeforces.com/gym/101840 A //Doubles
DevSkills 475: Bunty's Xor Game (4) //[BITS][GAME THEORY]
https://www.devskill.com/CodingProblems/ViewProblem/489 (5) //[NICE][FACTORISATION]
DevSkills 534 (4) //[BITSET][COMBINATIONS]
http://mirror.codeforces.com/gym/101650 D //Not hard — more coding + printing
13286 — Ingredients (4) //[NICE][DAG] Classical
8299 — Bricks (5) //[NICE][COMBINATORICS][SORTING]
http://mirror.codeforces.com/contest/934/my (4) //Subsequence
http://mirror.codeforces.com/contest/922/problem/E (5) //find max mana
http://mirror.codeforces.com/contest/920/problem/D (4) //[NICE][KNAPSACK-MODULO][GREEDY]
http://mirror.codeforces.com/contest/919/problem/D (4) //[NICE][DFS][CYCLE][DAG]
http://mirror.codeforces.com/contest/914/problem/C (3) //[DIGITS][BINARY]
http://mirror.codeforces.com/contest/913/problem/E (5) //[NICE][EXPRESSION]
http://mirror.codeforces.com/contest/148/problem/E (5) //[DP][PREFIX SUM][GREED]
http://www.spoj.com/problems/PALMKR/ (4) //Classical palindrome + print + lexicography
http://mirror.codeforces.com/contest/146/problem/E (5) //[NICE][COMBINATORICS][OBSERVATION]
http://mirror.codeforces.com/contest/909/problem/C (4) //[NICE][CLASSICAL][EASY]
7785 — m-ary Partitions (4) //Combinatorics
http://mirror.codeforces.com/contest/133/problem/E (4) //[IMPLEMENTATION]
http://mirror.codeforces.com/contest/126/problem/D (5) //[NICE]//Decomposet DP//Own hash-map
http://mirror.codeforces.com/contest/910/problem/B (3) //Or many other ways
6154 RNA Secondary Structure (5) //[NICE] Unoptimal might work too
https://arc087.contest.atcoder.jp/tasks/arc087_b (4) //[VERY NICE][OBSERVATION]
http://mirror.codeforces.com/contest/903/problem/F (5) //[VERY NICE][BITMASK][BRUTE]
http://mirror.codeforces.com/contest/903/problem/A (2) //Easy knapsack-like // Low constraints
http://mirror.codeforces.com/contest/900/problem/E (4) //[NICE]//Patter-match: FFT or KMP or Brute-Force
http://mirror.codeforces.com/contest/118/problem/D (3) //[COMBINATORICS][LOW-CONSTRAINTS]
http://mirror.codeforces.com/contest/115/problem/E (5) //[VERY NICE][SEGMENT TREE]
http://mirror.codeforces.com/contest/116/problem/D (3) //CLASSICAL[LOW-CONSTRAINTS]
10128 Queue (uva) (4) //One possibility is bitmask — second combinatorics
http://mirror.codeforces.com/contest/110/problem/C (3) //[EASY]// Greedy/math works too
8078 — Bracket Sequence (4) //[VERY NICE][DP-LINKS]
http://mirror.codeforces.com/contest/106/problem/C (3) //[NICE][EASY]
http://mirror.codeforces.com/contest/895/problem/C (4) //[NICE]
8024 Stack Construction (4) //[NICE] Palindromic style — but not exactly
7708 — Cubes (6) //[MATH]
http://mirror.codeforces.com/contest/888/problem/F (6) //[NICE][FLAG]
http://www.spoj.com/problems/ACQUIRE/ (5) //[NICE][CH-OPT]
http://mirror.codeforces.com/contest/319/problem/C (6) //[NICE][CH-OPT]
http://www.spoj.com/problems/NKLEAVES/ (5) //[NICE][DC]
http://mirror.codeforces.com/contest/76/problem/D (4) //[BITS][OVERFLOW]
http://mirror.codeforces.com/contest/73/problem/C (4) //[NICE][EASY][TRY-ALL-LETTERS]
http://mirror.codeforces.com/contest/67/problem/C (4) //[NICE][LEAVENSTEIN]
http://mirror.codeforces.com/contest/67/problem/A (3) //[EASY][PRINTING][OTHER POSSIBLE WAYS]
http://mirror.codeforces.com/contest/55/problem/D (5) //[NICE][DIGITS][EFFICIENT]
http://mirror.codeforces.com/contest/56/problem/D (4) //String modification + printing [NICE]
http://mirror.codeforces.com/contest/58/problem/E (6) //[NICE][IMPLEMENTATION]
UVA 12181
https://devskill.com/CodingProblems/ViewProblem/21
https://devskill.com/CodingProblems/ViewProblem/37
https://devskill.com/CodingProblems/ViewProblem/71
https://devskill.com/CodingProblems/ViewProblem/103
https://devskill.com/CodingProblems/ViewProblem/107
https://devskill.com/CodingProblems/ViewProblem/115
https://devskill.com/CodingProblems/ViewProblem/126
https://devskill.com/CodingProblems/ViewProblem/131
https://devskill.com/CodingProblems/ViewProblem/134
https://devskill.com/CodingProblems/ViewProblem/174
https://devskill.com/CodingProblems/ViewProblem/186
https://devskill.com/CodingProblems/ViewProblem/201
https://devskill.com/CodingProblems/ViewProblem/338
https://devskill.com/CodingProblems/ViewProblem/368
https://devskill.com/CodingProblems/ViewProblem/392
https://devskill.com/CodingProblems/ViewProblem/399
https://www.hackerrank.com/contests/world-codesprint-5/challenges/mining //Opti
UVA 12915 //Opti
UVA 12524 //Opti
http://mirror.codeforces.com/problemset/problem/631/E //CH
https://devskill.com/CodingProblems/ViewProblem/6
https://devskill.com/CodingProblems/ViewProblem/11
11552 UVA (3)
12172 UVA (3)
4507 LA (5)
4510 LA (5) [+ geometry]
12181 UVA (6)
http://mirror.codeforces.com/contest/729/problem/F 6
http://mirror.codeforces.com/contest/735/problem/E 9
http://mirror.codeforces.com/contest/731/problem/E 5
12030 UVA (4)
http://mirror.codeforces.com/contest/721/problem/E 7
http://mirror.codeforces.com/contest/742/problem/D 4
12040 UVA (5)
http://mirror.codeforces.com/contest/712/problem/D 5
13162 UVA (6)
http://mirror.codeforces.com/contest/743/problem/E 6
11908 UVA (3)
11932 UVA (4)
http://mirror.codeforces.com/contest/745/problem/E (7)
11806 UVA (4)
http://mirror.codeforces.com/contest/747/problem/F (5)
11843 UVA (4)
http://mirror.codeforces.com/contest/752/problem/E (5)
http://mirror.codeforces.com/contest/703/problem/E (7)
11753 UVA (4)
11725 UVA (5)
http://mirror.codeforces.com/contest/722/problem/E (9)
http://mirror.codeforces.com/contest/760/problem/F (8)
11795 UVA (3)
11654 UVA (4)
11523 UVA (5)
11404 UVA (4)
11432 UVA (4)
11451 UVA (4) //C==20 mistake in statement
11301 UVA (4)
http://mirror.codeforces.com/contest/762/problem/D 5
11361 UVA (4) //digit DP
11365 UVA (7)
11391 UVA (4) //easy+implementation
11394 UVA (3)
11218 UVA (2)
11125 UVA (4) //slightly implementation
11076 UVA (3)
11081 UVA (4) //3 string subsequences (beware of fail)
http://mirror.codeforces.com/contest/678/problem/E (5) //bitset dp + probability
http://mirror.codeforces.com/contest/766/problem/C (4)
http://mirror.codeforces.com/contest/667/problem/C (3)
http://www.spoj.com/problems/MOVIFAN/ (3)
http://www.spoj.com/problems/ORDSUM23/ (3)
http://www.spoj.com/problems/DIVSEQ/ (4) //N^3 (but better...) works fine
http://mirror.codeforces.com/contest/633/problem/F (7) //Tree dp
http://www.spoj.com/problems/ADJDUCKS/ (4) sort + pick 2-3 continous O(N)
http://www.spoj.com/problems/JLNT/ (4) //pick 0 or 2 | 1e3*5e3
http://www.spoj.com/problems/TPCPALIN/ (5) //500^3 works (3rd countable)
http://www.spoj.com/problems/COLORSEG/ (4) //50^4==OK 50^4log(N)=TLE NICE
http://www.spoj.com/problems/POWERCAR/ (3) //1e3*1e3*2 — follow rules
http://www.spoj.com/problems/INGRED/ (5) //TSP-like [reduce + go]
http://www.spoj.com/problems/BADXOR/ (4) //classical subsets
http://www.spoj.com/problems/SPCO/ (5) //64*64*2 DP {OPT: prime O(1) + clear only half}
http://www.spoj.com/problems/WAYHOME/ (5) //NICE: 1) 1*1 b)12,1,**,2
http://www.spoj.com/problems/NFURY/ (2) //Minimal sum of squares
http://www.spoj.com/problems/GDIL/ (3) //combinatorics
http://mirror.codeforces.com/contest/791/problem/D (5) //Tree
http://mirror.codeforces.com/contest/791/problem/E (6) //V,K,X — pick any
http://mirror.codeforces.com/contest/789/problem/C (3)
13176 (4) //N^6
13179 (5) //NICE [Ath][Bth][TimeDiff]
http://mirror.codeforces.com/contest/796/problem/E (6) //NICE: N*P*K*K (WC can't happen!)
http://mirror.codeforces.com/contest/797/problem/E (4) //NICE: Almost BF-able (but care of low K)
http://mirror.codeforces.com/contest/793/problem/D (3) //NICE & EASY: begin/end/actual/USED
http://mirror.codeforces.com/contest/803/problem/E (4) //State search — many IF's (EASY)
http://mirror.codeforces.com/contest/805/problem/F (7) //NICE: DP on tree + fast BF + hack
http://mirror.codeforces.com/contest/808/problem/E (5) //NICE!
http://mirror.codeforces.com/contest/811/problem/C (4) //Precalculate + DP (greedy thinking)
10817 UVA 4 //Easy but slightly implementation
10859 UVA 4 //Nice — on tree .. but for a reason small constrains
10898 UVA 4 //Hash is lesser than 1e6 .. try everything
http://mirror.codeforces.com/contest/812/problem/B (3) //Not only DP, yet imho easiest ..many spec cases
http://mirror.codeforces.com/contest/813/problem/D (5) //VERY VERY NICE — N*N (none picked between a/b)
http://mirror.codeforces.com/contest/814/problem/E 5 //VERY NICE — Harder imple: Combinatorics
http://mirror.codeforces.com/problemset/problem/816/E (6) //NICE — Tree (hard 2C complexity)
http://mirror.codeforces.com/contest/837/problem/D (5) //NICE — yet kinda pain [must be iterative]
http://www.spoj.com/problems/AUT/ (4) //NICE — K is interesting ~ at most 1600
http://www.spoj.com/problems/GNYR04C/ (3) //Easy — Nice idea [Big→ Low approach]
http://www.spoj.com/problems/TIEROPE/ (4) //Process 2*L ~ otherwise pick BIG
http://www.spoj.com/problems/IITKWPCE/ (4) //Palindromes [efficiency!] — NICE!
IITKWPCD SPOJ (4) //+Slightly geometry
UVA 1496 //[Steiner's Tree] Very Nice (8)
http://www.spoj.com/problems/LKS/ (3) //Classical knapsack
http://www.spoj.com/problems/UOFTAE/ (3) //Easy & Sympatic DP
http://www.spoj.com/problems/DCOWS/ (4) //Very NICE (sort + GO)
http://www.spoj.com/problems/FARIDA/ (3) //Easy & Sympatic ((u+1) | Price+(u+2))
http://www.spoj.com/problems/AU7_5/ (2) //EASY: dyn(n-1)+dyn(n-k-1)
http://www.spoj.com/problems/NAIVELOK/ (4) //NICE [depalindromisation]
http://mirror.codeforces.com/contest/846/problem/C (4) //With print
http://www.spoj.com/problems/CNT_LUCK/ (4) //Number (binary) dp [NICE] {ull care 0-1}
http://www.spoj.com/problems/MAY99_4/ (3) //Almost combinatoric Sub and 0/1,1/0
http://www.spoj.com/problems/GEEKOUNT/ (4) //Number dp
http://www.spoj.com/problems/MUTDNA/ (4) // N*2 (turned?) [not sure if grd poss.]
http://www.spoj.com/problems/RIOI_3_2/ (5) //VERY NICE (easy imple — Number Theory thinking)
http://www.spoj.com/problems/MAXWOODS/ (3) //NICE [EASY][GRID]
http://www.spoj.com/problems/DIEHARD/ (3) //Easy — prolly solvable by greedy (but dp is easier)
http://www.spoj.com/problems/DCEPC810/ (4) //VERY VERY NICE — Subsequence 2pointers+2bools
http://www.spoj.com/problems/EQ2/ (4) //NICE: Digit + Carry (from back) — iff-party
http://www.spoj.com/problems/DCEPC501/ (3) //NICE & EASY
http://www.spoj.com/problems/NUMTSN/ (4) //NICE — Thinking or Opti
http://www.spoj.com/problems/GONE/ (4) //NICE & EASY [digits]
http://www.spoj.com/problems/RAONE/ (4) //NICE & EASY [digits] — almost similar as above
http://www.spoj.com/problems/STRSEQ/ (4) //VERY VERY NICE — Next-Function
http://www.spoj.com/problems/MYQ8/ (4) //VERY NICE — 3x3 tic-tac-toe [implementation]
http://mirror.codeforces.com/contest/859/problem/C (3) //Easy+Sympathic [PrefixSumOptional]
http://mirror.codeforces.com/contest/859/problem/D (4) //NICE [Probabilities]
http://www.spoj.com/problems/UNICA/ (4) //VERY NICE [Posibilities][Print][Classical]
http://www.spoj.com/problems/KOPC12H/ (4) //NICE Digit-DP
http://www.spoj.com/problems/DRACULA/ (4) //NICE Digit-DP (Both sides) — iterate by sum
http://www.spoj.com/problems/ABCPATH/ (3) //DP over dfs (maybe without dp works too?)
http://www.spoj.com/problems/BEHAPPY/ (2) //Easy one — low constraints
http://www.spoj.com/problems/STRCOUNT/ (4) //No input (over bits)
http://mirror.codeforces.com/contest/855/problem/B (2) //prolly not even necessary
http://mirror.codeforces.com/contest/855/problem/C (4) //dp on tree
http://mirror.codeforces.com/contest/855/problem/E (5) //VERY NICE — Digits & Bitmask & Query (learning!)
http://www.spoj.com/problems/PAINTWAL/ (6) //VERY NICE — Imho hard (opti could beat)
http://www.spoj.com/problems/ADFRUITS/ (3) //Very simple (substring == subsequence)
http://www.spoj.com/problems/MAIN113/ (2) //NICE but somehow too low constraints
http://www.spoj.com/problems/MAIN112/ (4) //NICE — Bitmask
http://mirror.codeforces.com/contest/864/problem/E (5) //VERY NICE — Sort
http://www.spoj.com/problems/NOVICE63/ (4) //NICE -On digits (binary)
http://www.spoj.com/problems/TUG/ (3) //NICE + Observation {N>100 == YES}
http://www.spoj.com/problems/DOMINO1/ (4) //Used map to solve it
http://www.spoj.com/problems/NY10E/ (2) //Easy dp
http://www.spoj.com/problems/MAIN72/ (3) //Easy knapsack
http://www.spoj.com/problems/NOVICE43/ (2) //Unbelievably low constraints
http://mirror.codeforces.com/contest/598/problem/E (4) //N^5 strategy works fine [VERY NICE]
http://www.spoj.com/problems/CHAIR/ (3) //Maybe combinatorics too?
http://www.spoj.com/problems/ACPC10D/ (3) //NICE — DAG traversal
http://www.spoj.com/problems/CPCRC1C/ (4) //Digits dp (return pair)
http://www.spoj.com/problems/BORW/ (3) //Inc+Dec sequence (small array)
http://mirror.codeforces.com/problemset/problem/16/E (5) //Bitmask [NICE]
http://mirror.codeforces.com/problemset/problem/18/E (5) //VERY NICE {no need for second iteration}
http://mirror.codeforces.com/contest/2/problem/B (5) //NICE — 2/5 are in-fact independent
http://mirror.codeforces.com/contest/4/problem/D (3) //Classical [FW works too] XY > xy
http://mirror.codeforces.com/contest/6/problem/D (4) //NICE (N^4)
http://mirror.codeforces.com/contest/321/problem/E (7) //VERY NICE — D&C Trick
http://mirror.codeforces.com/contest/868/problem/F (8) //VERY VERY NICE D&C Trick — With MO Principal
http://mirror.codeforces.com/contest/8/problem/C (5) //NICE — Masks [N*2^N]
http://mirror.codeforces.com/contest/868/problem/E (8) //VERY NICE — HARD — on tree
http://mirror.codeforces.com/contest/10/problem/D (4) //LCIS [NICE]
http://mirror.codeforces.com/contest/13/problem/C (5) //NICE [sorting][only elements from array]
http://mirror.codeforces.com/contest/17/problem/C (5) //[NICE][iterative-sparse][+idea]
http://mirror.codeforces.com/contest/19/problem/B (4) //Knapsack (after good look)
http://mirror.codeforces.com/contest/30/problem/C (4) //Probabilities + (slight)GEO
http://mirror.codeforces.com/contest/31/problem/E (4) //[NICE]
http://mirror.codeforces.com/contest/41/problem/D (4) //With printing
http://www.spoj.com/problems/ADABRANC/
https://www.spoj.com/problems/CONSEC/ (4) //[NICE][OFFLINE]
https://mirror.codeforces.com/gym/102006/problem/C (4) //[NICE][BRUTE-FORCE]
http://mirror.codeforces.com/gym/101962/problem/J (5) //[VERY NICE][TREE-FAT][SPARSE]
http://mirror.codeforces.com/contest/915/problem/F (6) //[VERY NICE][SORTING]
http://mirror.codeforces.com/contest/141/problem/E (6) //[NICE][SPANNIG TREE]
7903 — Pandaria (7) //[VERY NICE][DSU][SORTING][MERGE][DFS]
http://mirror.codeforces.com/contest/110/problem/E (4) //[NICE][COMBINATORICS][TREE]
http://mirror.codeforces.com/contest/90/problem/E (5) //[NICE][DSU-LIKE-LINKS][SIMULATION]
http://mirror.codeforces.com/contest/87/problem/D (5) //[VERY NICE][SORTING][COMPRES][DFS]
http://mirror.codeforces.com/contest/884/problem/E (5) //[VERY NICE][MEMORY SPARSE]
http://mirror.codeforces.com/contest/60/problem/D (6) //[NICE][Pythagorean Triples][Gen over max!]
UVA 10947
UVA 12363
LA 3833
http://mirror.codeforces.com/problemset/problem/742/D //+DP
UVA 10178
http://mirror.codeforces.com/contest/723/problem/F 7
13153 UVA (5)
13169 UVA (3)
11987 UVA (3)
11474 UVA (4)
http://www.spoj.com/problems/BTCODE_G/
http://mirror.codeforces.com/problemset/problem/691/D
Gym 101174K [2016-2017 ACM-ICPC Southwestern European Regional Programming Contest (SWERC 2016)]
UVA 10583
LightOJ 1003
http://mirror.codeforces.com/problemset/problem/731/C
UVA 793
UVA 11966
https://www.codechef.com/problems/COZIC
3939 [LA]
UVA 11503
http://mirror.codeforces.com/problemset/problem/755/C
UVA 1395
http://mirror.codeforces.com/contest/687/problem/D 6
http://mirror.codeforces.com/contest/680/problem/E 7 //+precalculation/brute force
http://mirror.codeforces.com/contest/766/problem/D 5
http://www.spoj.com/problems/LEXSTR/ (3) //Nice na stringu
http://mirror.codeforces.com/contest/805/problem/C 3 //NICE (dijkstra like :P)
http://www.spoj.com/problems/IITKWPCI/ (3) //VERY NICE
http://www.spoj.com/problems/FRNDCIRC (3) //Classical DSU (NICE for practice)
http://www.spoj.com/problems/FOXLINGS/ (3) Easy — just renumbering
http://www.spoj.com/problems/NITTROAD/ (4) //Process from back
http://www.spoj.com/problems/SHAHBG/ (2) //DSU not needes (simulated by array)
http://mirror.codeforces.com/contest/598/problem/D (3) //Can be solved with DFS too
http://mirror.codeforces.com/contest/9/problem/E (4) //Making one big cycle
http://mirror.codeforces.com/contest/25/problem/D (4) //Could be done linear too
http://mirror.codeforces.com/contest/28/problem/B (4) //NICE [imho bad statement]
http://mirror.codeforces.com/contest/876/problem/D (4) //DSU adjacent + visited
http://mirror.codeforces.com/contest/875/problem/F (6) //NICE — Maximum cactus-forest [kruskal-like]
http://mirror.codeforces.com/gym/101879/problem/C (6) //[VERY NICE][DFS]
http://mirror.codeforces.com/contest/907/problem/F (7) //[MAGIC]
UVA 10299
UVA 10990
https://www.codechef.com/problems/SMPLSUM
https://www.codechef.com/problems/COZIE
http://www.spoj.com/problems/LCMSUM/
Gym 100975F [2003-2004 Petrozavodsk Summer Training Camp, Saratov SU Contest]
UVA 13132
http://www.spoj.com/problems/GCDEX/
UVA 12995
http://www.spoj.com/problems/TIP1/
UVA 11327
LightOJ 1007
http://www.spoj.com/problems/ETF/
Project Euler #72: Counting fractions
http://www.spoj.com/problems/DCEPCA03/
http://www.spoj.com/problems/NAJPWG/ 4 //Gauss-Euler
http://www.spoj.com/problems/DCEPC12G/ (5) //Do what is written there
http://www.spoj.com/problems/INVPHI/ (5) //Inverse euler
https://mirror.codeforces.com/gym/102006/problem/H (4) //[SORTING][OBSERVATION]
http://mirror.codeforces.com/gym/101650 I //[NICE][GRAPHS]// Theory is useful
13246 — Chained Words (4) //[NICE][LEXICOGRAPHICAL]
UVA 10735
http://mirror.codeforces.com/contest/789/problem/D //Adj EG + Self/everything
http://mirror.codeforces.com/contest/21/problem/D (5) //[NICE][EulerTour+DP]
http://mirror.codeforces.com/contest/36/problem/E (6) //VERY NICE [4odd is hardest]
http://www.spoj.com/problems/ADAHW/ [RHO][Number Theory]
http://www.spoj.com/problems/ADADIGIT/ [Permutations]
https://www.spoj.com/problems/PRIMEP/ (5) //[VERY NICE][SEGMENT][BS][SIEVE]
https://mirror.codeforces.com/gym/101981 J //[NICE][DIVIDE]
http://mirror.codeforces.com/gym/101801 B
UVA 13067
Project Euler #108: Diophantine reciprocals I
http://www.spoj.com/problems/CHGROOM/
Gym 101370A [2009-2010 Summer Petrozavodsk Camp, Petr Mitrichev Contest 5]
http://mirror.codeforces.com/problemset/problem/837/E
http://www.spoj.com/problems/PSYCHOT/
http://www.spoj.com/problems/FACTDIV/
http://www.spoj.com/problems/NOSQ/
http://www.spoj.com/problems/FCDC/
http://www.spoj.com/problems/NFACTOR/
http://www.spoj.com/problems/ABA12D/
http://www.spoj.com/problems/PSTR/
http://www.spoj.com/problems/AMR11E/
http://www.spoj.com/problems/FACT1/
http://www.spoj.com/problems/FACT2/
https://www.hackerearth.com/problem/algorithm/gold-at-lolympics/
12005 UVA (7)
12062 UVA (6)
11960 UVA (3)
http://www.spoj.com/problems/FACTCG2/ (3)
http://www.spoj.com/problems/FACT0/ (4)
http://mirror.codeforces.com/contest/546/problem/D 5
http://mirror.codeforces.com/contest/222/problem/C 6
http://www.spoj.com/problems/COMDIV/ 3
http://www.spoj.com/problems/SINEGGS/ 3
http://www.spoj.com/problems/BDOI16B/ 4
http://www.spoj.com/problems/HG/ 4 //Map == OK
11099 UVA (3) //factor + recursion
13194 UVA (3) //factorize+generate /or just check
13191 UVA (6) //Pollard-Rho
http://mirror.codeforces.com/contest/818/problem/E (4) // Efficient + Two Pointers
http://mirror.codeforces.com/contest/831/problem/F (6) //MAGIC
http://mirror.codeforces.com/contest/839/problem/D (4) // Combinatorics + IE
http://www.spoj.com/problems/SAS002/ (5) //Find all divisors (big numbers)
http://www.spoj.com/problems/GCDS/ (4) //Lowest unused prime
http://www.spoj.com/problems/IITKWPCF/ (4) //Nonprime divisors of N/2
http://mirror.codeforces.com/contest/851/problem/D (4) //Properties of GCD + factor: NICE
http://www.spoj.com/problems/PTIME/ (3) //Low bounds — check each prime independently
http://www.spoj.com/problems/MAIN12B/ (3) //NICE [Factorization][Sort][Unique]
http://www.spoj.com/problems/AMR11E/ (2) //2664 is the biggest
http://www.spoj.com/problems/GCPC11A/ (4) //Very nice — factorize + divide N by powers
http://www.spoj.com/problems/AMR10C/ (3) //Maximum of factor-powers
http://www.spoj.com/problems/ADABEHIVE/ [2D]
http://www.spoj.com/problems/ADACABAA/ [2D][Sparse]
https://mirror.codeforces.com/contest/1191/problem/F (5) //[NICE][SORTING]Or similar DS
https://mirror.codeforces.com/gym/102001/problem/H (4) //[NICE][GREEDY]
https://toph.co/p/easy-prime (4) //[EASY][SIEVE]
https://toph.co/p/mario-and-princess-peach (5) //[NICE][DP][SEGMENT TREE][MAX]
http://mirror.codeforces.com/gym/101628/problem/B (5) //[NICE][SPARSE][STL]
http://mirror.codeforces.com/gym/100112 (4) [B] //[NICE][INVERSION][OBSERVATION]
http://mirror.codeforces.com/gym/101982 (7) [I] //[VERY NICE][INVERSION][OBSERVATION]
http://mirror.codeforces.com/gym/101908/problem/C (4) //[MATH][INVERSION]
http://mirror.codeforces.com/gym/101889 (5) //[NICE] normalize
DevSkills-422: Double Pairs (4) //[NICE] normalize
7591 — Distribution Center (4) //[NICE][SORTING]
http://mirror.codeforces.com/contest/903/problem/D (5) //[NICE][BIG]
http://mirror.codeforces.com/contest/102/problem/D (4) //[NICE][+DP][NORMALIZE]
http://mirror.codeforces.com/gym/101047/problem/J [2D]
http://www.spoj.com/problems/MATSUM/ [2D]
https://devskill.com/CodingProblems/ViewProblem/300
http://mirror.codeforces.com/contest/707/problem/E 7 [2D]
http://mirror.codeforces.com/contest/749/problem/E 8
http://mirror.codeforces.com/problemset/gymProblem/101055/D 5 [2D]
11240 UVA (4)
http://mirror.codeforces.com/contest/459/problem/D (4) //[NICE][SWEEPING]
http://mirror.codeforces.com/contest/61/problem/E (4) //[NICE][CLASSICAL][2*FW][NORMALIZE]
http://mirror.codeforces.com/contest/669/problem/E 5 //fenwicks — sparse
http://mirror.codeforces.com/contest/777/problem/E 4 //MAXIMUM
http://www.spoj.com/problems/TULIPNUM/ 4 //inc — 1 nor+num|sum(A[B],A[E])
http://mirror.codeforces.com/contest/799/problem/C 3 //MAX FW (but possibly easier?)
http://mirror.codeforces.com/contest/831/problem/E 4 //MAP to get ORDER — FW == LIST
http://www.spoj.com/problems/SAS001/ (4) //Nice — number of inversions + 2P
http://www.spoj.com/problems/TPGA/ (4) //NICE — Lesser*(N-i-1)!
http://www.spoj.com/problems/SGIFT/ (4) //BS works too
http://www.spoj.com/problems/SUMSUM/ (5) //Bit-by-Bit cnt 0/1
http://www.spoj.com/problems/AKVQLD03/ (3) //Classical fenwick — easy
http://www.spoj.com/problems/ZIGZAG2/ (6) //Very nice — FW + BS + DP
http://mirror.codeforces.com/contest/849/problem/E (7) //2D Fenwick / ST+TP [NICE]
http://www.spoj.com/problems/CRAYON/ (5) //VERY NICE [2*FW — begin + end]
http://www.spoj.com/problems/NITT8/ (4) //Norm. + Store indices in MAX-Fenwick [REVERSE] [VERY NICE]
http://www.spoj.com/problems/DCEPC705/ (4) //NICE! Sort + Fenwick
http://www.spoj.com/problems/DCEPC206/ (3) //NICE & EASY
http://www.spoj.com/problems/KOPC12G/ (4) //N Fenwick trees
http://www.spoj.com/problems/TRIPINV/ (4) //2xFenwick (triples counting)
http://mirror.codeforces.com/contest/597/problem/C (4) //[VERY NICE] 11*Fenwick
http://mirror.codeforces.com/contest/12/problem/D (4) //NICE [triplet-comparing][sort]
https://www.spoj.com/problems/NARHIL/ // Sugested by ak07_
http://www.spoj.com/problems/ADAMATCH/
https://toph.co/p/play-the-lottery (7) //[VERY NICE][D&C][MODULAR]
UVA 12633
6886 — Golf Bot [LA]
http://www.spoj.com/problems/POLYMUL/en/
Gym 100960C [2015-2016 Petrozavodsk Winter Training Camp, Nizhny Novgorod SU Contest]
https://www.codechef.com/problems/APRPS
https://www.codechef.com/problems/POLYEVAL
http://www.spoj.com/problems/TSUM/ 5
13182 UVA 5 //ACTG hamming
http://mirror.codeforces.com/contest/827/problem/E (8) //MAGIC
http://www.spoj.com/problems/MAXMATCH/ 5 //abc hamming
https://www.spoj.com/problems/DISGRAPH/ (5) //Stoer-Wagner [global]
https://mirror.codeforces.com/gym/101981 I //[NICE]
http://mirror.codeforces.com/gym/101982 E //[VERY NICE][GRID]
http://mirror.codeforces.com/gym/101845/problem/F (4) //Basic
http://mirror.codeforces.com/gym/101908/problem/G (4) //[NICE][MATCHING][BS]
http://www.spoj.com/problems/FASTFLOW/en/ //Raw (no sauce)
http://mirror.codeforces.com/contest/78/problem/E (5) //NICE [Matching-like][+BFS]
4322 — Destroying the bus stations (Live Archive)
11380 — Down Went The Titanic (UVA) //Interesting grid problem
6395 — Surely You Congest (LA) //VERY NICE [slightly advanced]
7204 — Blood groups (LA)
http://mirror.codeforces.com/gym/100963 (Flame of Nucleus — F)
11167 — Monkeys in the Emei Mountain //Also harder (imho)
http://mirror.codeforces.com/problemset/problem/653/D (+BS)
13000 — VIP Treatment (+BS)
1242 — Necklace
https://www.deadline24.pl/assets/problemsets/dl24.elim.2017.B.en.pdf (DEADLINE 24 problem — not sure if it can be submited :O)
3487 — Duopoly (Near matching)
http://mirror.codeforces.com/problemset/problem/727/D
http://mirror.codeforces.com/problemset/problem/704/D [Also advanced]
5418 — A Plug for UNIX (LA)
4957 — Fake scoreboard (LA) //If I remember well, other solutions was also possible
1155 — Power Transmission (LOJ) //(classical)
https://www.codechef.com/problems/ROBOTDAG //Ford-Fukherson
10804 — Gopher Strategy (UVA)
11506 — Angry Programmer (UVA) //Nodes division
10511 — Councilling (UVA)
563 — Crimewave
1306 — The K-League (UVA)
1345 — Jamie's Contact Groups
10092 — The Problem with the Problem Setter
Problem B. Roller Coaster Scheduling (GCJ — 2017)
259 — Software Allocation (UVA)
5905 — Pool construction (LA) //Imho harder
10480 — Sabotage
http://mirror.codeforces.com/contest/808/problem/F 6 //NICE — nontrivial (max matching with bigger flows)
http://mirror.codeforces.com/contest/847/problem/J 6 //Probably not flows — matching-like
http://www.spoj.com/problems/ADAHOSE/ [DUAL-GRAPH]
http://mirror.codeforces.com/contest/903/problem/G (6) //[VERY NICE][SEG-TREE][CUT]
3837 [LA] //Stable Marriage
UVA 1175 //Stable Marriage
11594 — All Pairs Maximum Flow (UVA)
http://www.spoj.com/problems/ADABLOOM/ //Maximum matching in general graph
11439 — Maximizing the ICPC //Maximum matching in general graph
1376 — Animal Run //Max flow on planar graph (Dual == shortest path over edges)
10989 — Bomb, Divide and Conquer //Stoer-Wagner — global cut
https://mirror.codeforces.com/contest/1202/problem/B (3) //[VERY NICE]
http://mirror.codeforces.com/gym/101845/problem/C
https://www.urionlinejudge.com.br/judge/en/problems/view/2676 (3) //simple FW
10724 UVA
UVA 117
http://mirror.codeforces.com/problemset/problem/21/D
UVA 1198
LightOJ 1086 //+DP
http://www.spoj.com/problems/INGRED/ //+DP
UVA 10048
UVA 125
Gym 101223C [2017 Facebook Hacker Cup, Round 1] //+DP
LightOJ 1221
UVA 423
UVA 12179 //+DP
UVA 1416
UVA 1233
UVA 10793
10099 UVA
UVA 869
LightOJ 1174
http://www.spoj.com/problems/ARBITRAG/ //Other algos shall work too
13211 UVA (5) //NICE — FW adding states
http://www.spoj.com/problems/ROHAAN/ (3) //Classical
http://mirror.codeforces.com/contest/25/problem/C (4) //Adding new edges .. need FW principal
http://mirror.codeforces.com/contest/33/problem/B (3) //NICE [dijkstra could work too]
http://www.spoj.com/problems/ADAGAME/ [DP]
http://www.spoj.com/problems/ADAGAME2/
http://www.spoj.com/problems/ADAGAME4/
http://www.spoj.com/problems/ADAQUBIC/
http://www.spoj.com/problems/ADAFIMBR/
http://www.spoj.com/problems/ADAGAME5/
http://www.spoj.com/problems/ADAXMAS/
https://mirror.codeforces.com/contest/1194/problem/D (4) //[OBSERVATIO][PATTERN]
https://mirror.codeforces.com/contest/1191/problem/E (4) //[NICE][IF][OBSERVATION]
https://www.spoj.com/problems/HUSGAME/ (4) //[VERY NICE][OBSERVATION][RECURSION]
https://www.spoj.com/problems/IBIGAME/ (5) //[VERY NICE][OBSERVATION][DP]
https://mirror.codeforces.com/gym/101981 A
https://mirror.codeforces.com/gym/102058/problem/F (4) //[NICE]
http://mirror.codeforces.com/gym/101801 F //[EASY][OBSERVATION][NIM]
http://mirror.codeforces.com/gym/101908/problem/B (5) //[NICE][NIMBERS][OBSERVATION]
http://mirror.codeforces.com/gym/101873 H //[VERY NICE][OBSERVATION][TREE] //LUP LUP
http://mirror.codeforces.com/gym/101808/problem/I (5) //[DP][OBSERVATION]
http://mirror.codeforces.com/contest/919/problem/F (6) //[NICE][HARD][IMPLE][BFS][TOPO][GRAF]
http://mirror.codeforces.com/contest/918/problem/D (4) //[NICE][DAG][DP][TREE]
http://mirror.codeforces.com/contest/914/problem/B (3) //[NICE][EASY][OBSERVATION][PARITY]
http://mirror.codeforces.com/contest/148/problem/D (4) //[EASY][DP][PROBABILITY]
http://mirror.codeforces.com/contest/138/problem/D (7) //[VERY NICE][DP][OBSERVATION]
https://arc087.contest.atcoder.jp/tasks/arc087_c (5) //[VERY NICE][TRIE][SEQUENCE]
http://mirror.codeforces.com/contest/120/problem/E (3) //[NICE][SYMETRY][PARITY]
http://mirror.codeforces.com/contest/88/problem/E (5) //[VERY NICE][PREFIX-XOR][NIMBERS][SQRT][MATH]
http://mirror.codeforces.com/contest/69/problem/D (4) //[NICE][DP] Reflection can be ignored
http://mirror.codeforces.com/contest/55/problem/C (4) //[NICE] Size of piece from border
http://mirror.codeforces.com/problemset/problem/255/E --MEX
https://devskill.com/CodingProblems/ViewProblem/91
https://devskill.com/CodingProblems/ViewProblem/364
Project Euler #96: Su Doku //Sudoku
11859 UVA 4
11863 UVA 4
11892 UVA 3 //Probably solved by many
11534 UVA 5
http://www.spoj.com/problems/VECTAR11/ 4 //Nsqrt(N) passes [with break]
http://mirror.codeforces.com/contest/768/problem/E (4) //NICE — Grundy
http://www.spoj.com/problems/SYNC13C/ (4) //2*DP {maybe not seeing sth}
http://mirror.codeforces.com/contest/787/problem/C (4)
http://mirror.codeforces.com/contest/794/problem/C (3) //Find optimal strategy: choose back/front
http://mirror.codeforces.com/contest/794/problem/E (5) //NICE Find stategy: Even/Odd
http://mirror.codeforces.com/contest/812/problem/E (7) //Advanced NIM strategy
http://www.spoj.com/problems/GAMEMVS/ (4) //Nimbers (Ai^X)<=Ai
http://www.spoj.com/problems/PLAYGAME/ (3) //Check pattern
http://www.spoj.com/problems/CHAOS_CC/ (4) //VERY NICE [nimbers]
http://mirror.codeforces.com/contest/851/problem/E (5) //Very nice [nimbers] [bitset]
http://www.spoj.com/problems/CHGROOM/ (4) //+Factorisation [NICE & Easy]: Win unless 2 prime factors
http://www.spoj.com/problems/EALP1/ (4) //NICE ~ Possible Moves of NIM
http://www.spoj.com/problems/GAME3/ (4) //VERY NICE — pattern watching [A145812]
http://www.spoj.com/problems/GAME2/ (5) //VERY NICE — https://community.topcoder.com/tc?module=Static&d1=match_editorials&d2=srm338 (CAKE)
http://www.spoj.com/problems/CF36D/ (5) //Pattern watching (care for 1)
http://mirror.codeforces.com/contest/15/problem/C (4) //VERY NICE [XOR: A,1,A+1,0..repeat]
http://mirror.codeforces.com/contest/39/problem/E (4) //Slightly [DP][MATH][ROUNDING]
http://mirror.codeforces.com/contest/63/problem/E (5) //[NICE][BITMASK-DP]
12910 — Snakes and Ladders [UVA]
UVA 10828
http://mirror.codeforces.com/gym/100923/problem/C
4963 [LA]
UVA 12849
Gym 100962A [2015-2016 Petrozavodsk Winter Training Camp, Moscow SU Trinity Contest][NICE]
UVA 10109 [NICE][HARD-WORK]
http://www.spoj.com/problems/ADAPICK/
http://www.spoj.com/problems/ADAKOHL/
https://mirror.codeforces.com/contest/1199/problem/B (2) //[NICE][SIMPLE]
https://mirror.codeforces.com/gym/101991/problem/J (5)
https://mirror.codeforces.com/gym/101991/problem/B (4)
https://mirror.codeforces.com/gym/102006/problem/I (4) //[VERY NICE][ITERATIVE]
https://mirror.codeforces.com/gym/102021 G //[3D]
https://mirror.codeforces.com/gym/102021 B //Path on circle
https://mirror.codeforces.com/gym/102058/problem/K (3) //[BRUTE-FORCE][FAIL]
https://mirror.codeforces.com/gym/101972/problem/C (4) //[EASY][POINTS DISTANCE][IMAGE]
http://mirror.codeforces.com/gym/101628/problem/C (4) //Circles intersection
http://mirror.codeforces.com/gym/100112 G //Special cases and so on — imple.
http://mirror.codeforces.com/gym/101982 G //[DISTANCE]
http://mirror.codeforces.com/gym/101845/problem/D (5) //[VERY NICE][POLYGON][MO]
http://mirror.codeforces.com/gym/101962/problem/G (5) //Angles
http://mirror.codeforces.com/gym/101908/problem/K
http://mirror.codeforces.com/gym/101879/problem/A (7)
http://mirror.codeforces.com/gym/101873 G //Pick's Theorem
http://mirror.codeforces.com/gym/101873 A //heavy implementation
http://mirror.codeforces.com/gym/101808/problem/E (5)
http://mirror.codeforces.com/gym/101808/problem/A (2)
http://mirror.codeforces.com/gym/101666 A
http://mirror.codeforces.com/gym/101726/problem/J (5) //[NICE][INTERSECTION][DS]
http://mirror.codeforces.com/gym/101650 F //Polygons + circles
http://mirror.codeforces.com/gym/101650 H //A few if's
http://mirror.codeforces.com/contest/908/problem/C (3)
http://mirror.codeforces.com/contest/140/problem/A (3) //Circles around bigger circle
http://mirror.codeforces.com/contest/136/problem/D (4) //+Brute-Force
http://mirror.codeforces.com/contest/127/problem/A (1) //Points distance
http://mirror.codeforces.com/gym/101597/problem/B (3) //Simply brute-force just the closest to points
http://mirror.codeforces.com/contest/70/problem/D (5) //Dynamic Convex Hull
https://icpc.kattis.com/problems/airport //Proposed by Tutis
https://www.hackerrank.com/contests/world-codesprint-7/challenges/elastic-rope/problem
https://devskill.com/CodingProblems/ViewProblem/20 [EASY]
UVA 10321 //Polygon intersection
UVA 11265 //Polygon point +/-
UVA 13112 //Polygon
10907 UVA [Area of polygon from a point]
3378 — Swamp Things [LA] — Maximum points on line
UVA 11768 //Discrete points
2542 [LA] //Arc size [formula]
UVA 1571 //As below [easier]
https://www.codechef.com/problems/ALLPOLY //[NICE] Point seeing polygon
http://www.spoj.com/problems/IITKWPCL/ //Point distance
UVA 11281 //circle~triangle
UVA 12921 //circle reconstruction
UVA 190 //circle from 3 points
UVA 12240 //pts>circle
UVA 438 //circle pt
LightOJ 1018 //Minimum # of lines through all pts [VERY NICE]
UVA 11008 //Similar as above
UVA 12830 //Biggest rectangle without points inside
UVA 11012 //Most distant points
UVA 1683 //Closest points
UVA 12389 //3D MH Closest Points
http://www.spoj.com/problems/AMR12C/ //Pt closest to all other points
http://www.spoj.com/problems/CLOPPAIR/ //Closest pair of points
UVA 10678 //Circles intersection
http://mirror.codeforces.com/problemset/problem/600/D //Circles intersection
LightOJ 1118 //Circles intersection
http://www.spoj.com/problems/CERC07C/en/ //Bounding circle
UVA-10005 //Bounding circle
2407 [LA] //Bounding Sphere
LightOJ 1120 //Rectangle's Union
LightOJ 1130 //Circle x Rectangle intersection
UVA 11177 //Circle x Convex Polygon
http://mirror.codeforces.com/problemset/problem/610/D //Lines intersections (axes parallel)
6263 [LA] //Pt in areas
LightOJ 1058 //# parallelograma
UVA 12931 //Common area of polygons
UVA 10301 //Intersecting circles
UVA 453 //Circles intersection
http://mirror.codeforces.com/problemset/problem/681/E //Circles intersection
UVA 920 //Lines intersecion (etc..)
UVA 12556
http://mirror.codeforces.com/problemset/problem/793/C //Intersection ans similar
UVA 11343 //Intersection of segments
UVA 866 //Intersection of segments
Gym 100190I [2011 ACM-ICPC East Central North America (ECNA 2011)] //Segment intersection
http://mirror.codeforces.com/gym/100917/problem/K
UVA 11686 //Segment intersection
LightOJ 1388
UVA 833 //Segment intersection
LightOJ 1196 //Points sides
UVA 10167 //Points sides
UVA 12818 //Arc & Point distance
http://www.spoj.com/problems/SICRANO/ //Point-line distance
http://mirror.codeforces.com/problemset/problem/614/C //Point-line distance
UVA 13117 //Point-line distance
UVA 12483 //Point-line distance
UVA 12173 //Point-line distance
UVA 10075 //Point distance on sphere
https://www.hackerrank.com/contests/booking-hackathon/challenges/nearby-attractions/problem //Pt sphr
UVA 535 //Point distance on sphere
UVA 10897 //Sphere tavelling
UVA 11817 //Sphere travelling
UVA 10316 //Sphere travelling
UVA 1469 //Fractions distance 3D
11930
12173 UVA 3
12194 UVA 4
11894 UVA 3
11769 UVA 7
11665 UVA 5
11509 UVA 4
11355 UVA 5
11265 UVA 6 //Nice one | polygon — cut/pt-check/area
11123 UVA 4 //Counting trapezoids
11177 UVA 6 //BS+Polygon/Circle intersection
11186 UVA 3
11008 UVA 5 //with DP → #intersected triangles
11012 UVA 5 //Nejvzdálenější body (Manhatton 3D)
11072 UVA 4 //Points v poly gonu
http://mirror.codeforces.com/problemset/problem/682/E 6 (biggest triangle)
http://mirror.codeforces.com/contest/672/problem/C 4 //easy — just think it up
http://mirror.codeforces.com/contest/667/problem/A 2 //vzorecky
http://mirror.codeforces.com/contest/793/problem/C 5 //EASY but beware of epsilons (NICE)
http://mirror.codeforces.com/contest/794/problem/B 2 //Can be done with BS
http://mirror.codeforces.com/contest/814/problem/D 5 //+DP on trees (NICE — but low geom.)
10750 UVA 3 //Closest points — try all pairs
http://mirror.codeforces.com/contest/820/problem/B 3 //Polygon angle find!
13213 UVA 5 //VERY NICE — Voronoi diagram (low constraints so not actually needed)
13215 UVA 3 //EASY — Sum areas and find side lengths
http://www.spoj.com/problems/IITKWPCC/ (5) //VERY VERY NICE — Nqrt(N)log(N)
http://www.spoj.com/problems/NNS/ (5) Closest points query [fake geometry] {__128}[NICE]
http://mirror.codeforces.com/contest/849/problem/B (3) //X-Product — side
http://www.spoj.com/problems/AMR12C/ (5) //Point closest to all other points (with speed)
http://www.spoj.com/problems/SICRANO/ (3) //Line-Point distance
http://www.spoj.com/problems/VCIRCLES/ (5) //Heavy geometrical ****
http://www.spoj.com/problems/CIRU/ (5) //Same as above [yet bigger constraints]
http://www.spoj.com/problems/THREETW1/ (4) //Fermat point search
http://www.spoj.com/problems/CLOPPAIR/ (4) //Closest pair of points
http://www.spoj.com/problems/MAXLN/ (2) //Some basic (4*r^2+.25)
http://www.spoj.com/problems/KOLICA/ (4) //VERY NICE [nasty iff party]
http://mirror.codeforces.com/contest/598/problem/C (4) //NICE ~ Precision! [ld]
http://mirror.codeforces.com/contest/18/problem/A (2) //EASY&FINE: Pythagoreas
http://mirror.codeforces.com/contest/40/problem/A (2) //[EASY][DISTANCE]
https://mirror.codeforces.com/contest/1182/problem/D (5) //[CENTRUM][OBSERVATION][DFS]
https://www.urionlinejudge.com.br/judge/en/problems/view/1562 (5) //[VERY NICE][QUEUE][GREEDY]
https://mirror.codeforces.com/gym/102001/problem/G (4) //[NICE][BS]
https://mirror.codeforces.com/gym/102006/problem/G (4) //[NICE][TOPOSORT][OBSERVATION]
https://mirror.codeforces.com/gym/102058/problem/B (6) //[VERY NICE][REVERSE-SIMULATION]
http://mirror.codeforces.com/gym/101666 H //[VERY NICE][GEOMETRY][DSU][EULER][PLANAR]
2827 [LA] //3Coloring
2243 [LA] //3Coloring
5603 [LA] //Coloring
UVA 1658 //Shortest paths
UVA 12821 //Shortest paths
http://mirror.codeforces.com/contest/27/problem/D (5)
11387 (UVA) 4
http://www.spoj.com/problems/VFRIEND2/ (5) //Graph possible check
http://mirror.codeforces.com/contest/859/problem/E (4) //VERY NICE (2 cases: CYCLE [x2] / TREE [x(Size+1)]
http://mirror.codeforces.com/contest/847/problem/C (2) //Forest making Easy&Nice
http://mirror.codeforces.com/contest/863/problem/C (3) //Cycle in states
https://mirror.codeforces.com/contest/1175/problem/D (4) //[NICE][PREPROCESS][SORTING]
https://mirror.codeforces.com/contest/1203/problem/F1 (5) //[VERY NICE][SORTING][CASES]
https://mirror.codeforces.com/contest/1176/problem/C (3) //[SIMPLE][NICE][IMPLE]
https://mirror.codeforces.com/contest/1176/problem/A (1)
https://mirror.codeforces.com/contest/1200/problem/B (3) //[SIMPLE][NICE]
https://mirror.codeforces.com/contest/1202/problem/A (2)
https://mirror.codeforces.com/contest/1181/problem/B (4) //[BIG]
https://atcoder.jp/contests/abc136/tasks/abc136_c (3) //[REVERSE]
https://mirror.codeforces.com/contest/1185/problem/C2 (4)
https://mirror.codeforces.com/contest/1185/problem/B (2) //[EASY]
https://mirror.codeforces.com/contest/1180/problem/B (3) //[IMPLEMENTATION][MATH]
https://mirror.codeforces.com/contest/1186/problem/D (4) //[IMPLEMENTATION]
https://mirror.codeforces.com/contest/1197/problem/B (3) //[BITONIC][IMPLE]
https://www.spoj.com/problems/DIVSTR/ (3) //[CUTE]
https://mirror.codeforces.com/gym/101981 E //[NICE][NORMALIZE][STACK]
https://mirror.codeforces.com/gym/102001/problem/L (3) //[BITS]
https://toph.co/p/passwords (2)
http://mirror.codeforces.com/gym/100112 (3) //[FINE]
http://mirror.codeforces.com/gym/101666 (4) //[NICE][QUEUE][DFS][EVENTS]
http://mirror.codeforces.com/gym/101806/problem/T (5) //[NICE][SEGMENT TREE][SORTING]
http://mirror.codeforces.com/contest/916/problem/B (3) //[BITS] FIRST & LAST
http://mirror.codeforces.com/contest/913/problem/C (3) //+[DP]
http://mirror.codeforces.com/contest/146/problem/D (4) //[NICE][CONSTRUCTION]
http://mirror.codeforces.com/contest/146/problem/C (3) //[EASY][NICE][TWO-CASES]
http://mirror.codeforces.com/contest/139/problem/D (4) //Muchas cases
7887 — Back to the Future (4) //[NICE][2*HEAP]
http://mirror.codeforces.com/contest/910/problem/A (2) //DP works too
http://mirror.codeforces.com/contest/125/problem/D (4) //Limited possibilities
http://mirror.codeforces.com/contest/902/problem/A (2) //Just keep last
http://mirror.codeforces.com/contest/898/problem/D (4) //[NICE][FENWICK/OR/PREFIX]
http://mirror.codeforces.com/contest/118/problem/C (4) //[NICE] — Try each digit (iterate in waves)
7706 — Pokemons (2) //Sweep and keep maximum
http://mirror.codeforces.com/contest/893/problem/D (4) //[NICE][SWEEP][MAXIMUM] — pay max when have to
http://mirror.codeforces.com/contest/892/problem/B (2) //Sweep from back
http://mirror.codeforces.com/contest/102/problem/C (3) //sort by frequency
https://devskill.com/CodingProblems/ViewProblem/419 (2) //Sweep from back
http://mirror.codeforces.com/contest/890/problem/C (3) //frequence
http://mirror.codeforces.com/contest/890/problem/B (2) //[EASY][REVERSE]
http://mirror.codeforces.com/contest/888/problem/B (2) //Equalize U/D and L/R
http://mirror.codeforces.com/gym/101597/problem/J (4) //[NICE][SWEEP]
http://mirror.codeforces.com/contest/76/problem/B (4) //[NICE][MATCHING-LIKE][2PTRS]
http://mirror.codeforces.com/contest/73/problem/B (4) //[IMPLEMENTATION][SORTING]
http://mirror.codeforces.com/contest/883/problem/K (4) //Nice — Two sweeps
http://mirror.codeforces.com/contest/49/problem/D (3) //NICE — 1010101 OR 0101010 [haming]
http://mirror.codeforces.com/contest/58/problem/C (4) //NICE — group trees by slopes
http://mirror.codeforces.com/contest/729/problem/D 3
http://mirror.codeforces.com/contest/729/problem/E 4
http://mirror.codeforces.com/contest/725/problem/D 4
http://mirror.codeforces.com/contest/725/problem/F 9
http://mirror.codeforces.com/contest/732/problem/E 5
http://mirror.codeforces.com/contest/727/problem/F 6
http://mirror.codeforces.com/contest/724/problem/D 5
http://mirror.codeforces.com/contest/723/problem/C 4
http://mirror.codeforces.com/contest/719/problem/B 2
http://mirror.codeforces.com/contest/712/problem/C 3
13152 UVA (4)
http://mirror.codeforces.com/contest/746/problem/E 5
http://mirror.codeforces.com/contest/746/problem/D 3
http://mirror.codeforces.com/contest/749/problem/C 3
11737 UVA (3)
11786 UVA (4)
11630 UVA (5)
11563 UVA (4)
11491 UVA (4)
11330 UVA (3)
11089 UVA (2)
http://mirror.codeforces.com/contest/884/problem/D (4) //PQ or Sort
http://www.spoj.com/problems/SQRMINSUM/ 3 //solve-able in O(N+M)-arrayqueue
http://www.spoj.com/problems/MSCHED/ 3 //sweep from back
http://www.spoj.com/status/ns=18780683 4 //all perm + A<B<C works
http://www.spoj.com/problems/NINJA7/ (3) //sort by diff
http://www.spoj.com/problems/NINJA2/ (4) //try all possib. (26)
http://mirror.codeforces.com/contest/767/problem/E (6)
http://mirror.codeforces.com/contest/637/problem/B (3) //NICE pro prvaky
http://mirror.codeforces.com/contest/777/problem/B (3) // -||-
http://mirror.codeforces.com/contest/777/problem/D (3) //just go from end
http://mirror.codeforces.com/contest/779/problem/C (3) //NICE pro prváky
http://www.spoj.com/problems/SPCU/ (2) //Easy — zamysleni (max int = index)
http://www.spoj.com/problems/LOPOV/ (4) //sort + queue (or just queue) NICE
http://mirror.codeforces.com/contest/792/problem/E (5) //T%S<=T/S + check proper
http://mirror.codeforces.com/contest/807/problem/E (5) //NICE — put asice P2 / rest — greedy from small
http://mirror.codeforces.com/contest/799/problem/E (5) //Many queues — but NICE
http://mirror.codeforces.com/contest/808/problem/C (3) //EASY
http://mirror.codeforces.com/contest/802/problem/B (4) //Priority by "next"
10850 UVA (4) //Queue a brute-force
http://mirror.codeforces.com/contest/813/problem/A (1) //Zahrivacka pro prvaky
10716 UVA (4) //NICE — always find closest pair
http://mirror.codeforces.com/contest/816/problem/C (3) //NICE — greater<lesser side
http://mirror.codeforces.com/contest/820/problem/D (5) //VERY NICE — O(N) -~- 5 events per number
http://mirror.codeforces.com/contest/818/problem/B (2) //Zahrivacka pro prvaky
http://mirror.codeforces.com/contest/822/problem/C (4) //Almost classical Sort+Queue
http://mirror.codeforces.com/contest/825/problem/C (2) //Nice & Easy
http://mirror.codeforces.com/contest/825/problem/D (3) //Update by modulo
http://mirror.codeforces.com/contest/835/problem/B (2) // Zahhrivacka pro prvaky
http://mirror.codeforces.com/contest/839/problem/B (3) //Nasty iffs — yet nice excersize
http://www.spoj.com/problems/PCPC12I/ (4) //Swipe MINIMUM from left/right [10^6-A[i] trick]
http://www.spoj.com/problems/AMR12I/ (3) //NICE a) MAX_SEG>=K b) (SEG_SIZE-1)/K+1
http://www.spoj.com/problems/BUSYMAN/ (2) //NICE&EASY — Sort + keep minimum
http://mirror.codeforces.com/contest/861/problem/C (3) //2+ but not same
http://www.spoj.com/problems/WORKB/ (3) //Simple "min" formula for each neighbor
http://mirror.codeforces.com/contest/864/problem/D (4) //VERY NICE — Frequency + unused
http://www.spoj.com/problems/ROADTRIP/ (4) //VERY NICE — Keeping last lesser
http://mirror.codeforces.com/contest/597/problem/B (3) //NICE [Classical]
http://www.spoj.com/problems/SHLIGHTS/ (4)
http://www.spoj.com/problems/MLK/ (3) //VERY NICE — Sum all prefix sums
http://mirror.codeforces.com/contest/867/problem/C (4) //NICE [IMPLE][2POINTERS][MID+EPS]
http://mirror.codeforces.com/contest/867/problem/E (5) //NICE [EASY-IMPLE][HARD-CONS]
http://mirror.codeforces.com/contest/18/problem/D (4) //+Big Integer
http://mirror.codeforces.com/contest/276/problem/D (4) //NICE — Find first mismatch bit (then 111...111)
http://mirror.codeforces.com/contest/3/problem/B (4) //Divide 1/2 [sort][2pointers]
http://mirror.codeforces.com/contest/3/problem/D (4) //?==) ..if open < 0: set max A-B to (
http://mirror.codeforces.com/contest/26/problem/B (4) // +1 ( | -1 ): -1, erase .. erase sum in the end
http://mirror.codeforces.com/contest/33/problem/A (2) //EASY [long-statement]
http://mirror.codeforces.com/contest/44/problem/E (2) //Try mins then try maxs
http://mirror.codeforces.com/contest/45/problem/D (3) //Priority-queue+'sort'
http://www.spoj.com/problems/ADACLEAN/
https://mirror.codeforces.com/contest/1200/problem/E (5) //[VERY NICE]
http://mirror.codeforces.com/gym/101808/problem/B (5) //[NICE][NUMBERS]
http://mirror.codeforces.com/gym/101741/problem/K (5) //[NICE][SQRT][PATTERN MATCHING]
7979 — Red Rover (3) //[NICE] //Many other ways to solve
http://mirror.codeforces.com/contest/898/problem/F (5) //[VERY NICE]//Hash by 10
http://mirror.codeforces.com/contest/114/problem/D (4) //[NICE] //N^2Log(N) might/might-not be OK
https://www.urionlinejudge.com.br/judge/en/problems/view/1503 (7) //[NICE][BS][OPTI]
Gym 101466E [2017 ACM-ICPC, Universidad Nacional de Colombia Programming Contest][NICE]
12012 UVA 4
http://mirror.codeforces.com/contest/727/problem/E 7
http://mirror.codeforces.com/contest/718/problem/D 8
11855 UVA 4
http://mirror.codeforces.com/contest/752/problem/D 5
http://mirror.codeforces.com/contest/825/problem/F 5 //String + Periods
http://mirror.codeforces.com/contest/835/problem/D 4 //Palindromes
http://www.spoj.com/problems/CF25E/ (5) //VERY NICE [IMPLE>CONCEPT]
http://mirror.codeforces.com/contest/7/problem/D (4) //Palindromes
http://mirror.codeforces.com/contest/19/problem/C (4) //[NICE]: Not a string
13300 — Ghost Hunting (4) //Hull + calipers passes
http://mirror.codeforces.com/gym/101982 M //[VERY NICE][HULL][TERNARY]
http://www.spoj.com/problems/GARDENHU/en/
2453 — Wall [LA]
UVA 13213
UVA 11096
Gym 100792G [2015-2016 ACM-ICPC, NEERC, Moscow Subregional Contest]
https://www.codechef.com/problems/KTHCON
http://mirror.codeforces.com/problemset/problem/605/C
UVA 218
UVA 11072
11168 UVA
UVA 12307
Gym 100963I [2007-2008 Summer Petrozavodsk Camp, Japanese Contest, 2007-08-29]
UVA 11243
UVA 10256
109 SCUD Busters
UVA 13024 [NICE]
UVA 10002
Gym 100886H [2015-2016 Petrozavodsk Winter Training Camp, Saratov SU Contest]
UVA 1139
UVA 681
UVA 811
https://www.codechef.com/problems/MGCHGEOM
UVA 11769 //3D
http://www.spoj.com/problems/ADACHESS/
http://www.spoj.com/problems/ADACHES2/
http://www.spoj.com/problems/ADAGAME5/
http://www.spoj.com/problems/ADAXMAS/
URI 1100 (3) //[BFS][KNIGHT]
https://www.codechef.com/problems/CHQUEENS (4) //[IMPLEMENTATION]
http://mirror.codeforces.com/contest/131/problem/E (4) //[NICE][STL][SORTING][QUEEN]
http://mirror.codeforces.com/contest/42/problem/B (4) //NICE — Checkmate check
UVA 10748 //bfs
LightOJ 1143
UVA 10196
http://www.spoj.com/problems/KNMOVE/
UVA 11352
http://www.spoj.com/problems/NAKANJ/ //BFS
LightOJ 1010
LightOJ 1171 //MM
2883 LA
UVA 439
http://www.spoj.com/problems/TRKNIGHT/ //??
2308 LA
http://www.spoj.com/problems/CCHESS/ //Dijkstra
http://mirror.codeforces.com/problemset/problem/630/H //[ROOKS][BIG][COMBINATORICS]
LightOJ 1005 //As above (but with real rooks)
LightOJ 1061 //Placing queens
UVA 11085
UVA 10094 //Queen placing [NICE][PATTERN]
https://devskill.com/CodingProblems/ViewProblem/383
11852 UVA (6)
http://www.spoj.com/problems/KLUG1/ (2) //Jumps of horse
http://www.spoj.com/problems/CODESPTD/ (5) //VERY NICE — DP [Queens]
http://mirror.codeforces.com/contest/3/problem/A (2) //Imple — Shortest path for king
http://mirror.codeforces.com/contest/38/problem/B (2) //NICE — Simple possition checking
https://mirror.codeforces.com/contest/1203/problem/A (1) //[FOR][IF]
https://mirror.codeforces.com/contest/1173/problem/A (1) //[IF]
https://devskill.com/CodingProblems/ViewProblem/584 (2)
https://mirror.codeforces.com/contest/1200/problem/A (2) //[EASY]
https://mirror.codeforces.com/contest/1182/problem/B (3) //[PRACTICE][GRID-MOVEMENT]
https://mirror.codeforces.com/contest/1201/problem/B (2)
https://mirror.codeforces.com/contest/1201/problem/A (2)
https://atcoder.jp/contests/abc136/tasks/abc136_a (1)
https://mirror.codeforces.com/contest/1199/problem/A (2) //[BF]
https://mirror.codeforces.com/contest/1183/problem/A (2)
https://mirror.codeforces.com/contest/1186/problem/A (1)
https://mirror.codeforces.com/contest/1178/problem/A (2)
https://mirror.codeforces.com/contest/1195/problem/A (2) //[ARRAY]
https://mirror.codeforces.com/contest/1191/problem/A
https://www.spoj.com/problems/MOZHSLM/ (3) //Two sweeps
https://www.spoj.com/problems/OVGDEL/ (3) //[NICE][EASY][FREQUENCY]
https://www.spoj.com/problems/VTV1001/ (2)
https://mirror.codeforces.com/gym/102001/problem/D (3)
https://mirror.codeforces.com/gym/102021 (7) //[VERY NICE]Easy thought but nice imple
https://mirror.codeforces.com/gym/101972/problem/E (2)
https://mirror.codeforces.com/gym/101972/problem/D (1) //[IF]
https://toph.co/p/full-pyramid (1)
http://mirror.codeforces.com/gym/101992/problem/F (2)
http://mirror.codeforces.com/gym/101628/problem/D (3)
http://mirror.codeforces.com/gym/100112 I //[NICE][STRINGS][BITMASKS]
http://mirror.codeforces.com/gym/100112 A
http://mirror.codeforces.com/gym/101982 L
http://mirror.codeforces.com/gym/101982 J
http://mirror.codeforces.com/gym/101982 A //Easy
http://mirror.codeforces.com/gym/101845/problem/H (2) //Dates
http://mirror.codeforces.com/gym/101801 L
http://mirror.codeforces.com/gym/101801 A
http://mirror.codeforces.com/gym/101864 C //Easy
http://mirror.codeforces.com/gym/101889/my H
http://mirror.codeforces.com/contest/934/problem/A (2)
http://mirror.codeforces.com/contest/922/problem/A (2) //Iff-party
http://mirror.codeforces.com/contest/914/problem/A (1)
http://mirror.codeforces.com/contest/916/problem/A (2) //Time
http://mirror.codeforces.com/contest/915/problem/B (2) //Formula / Iff
http://mirror.codeforces.com/contest/915/problem/A (1)
http://mirror.codeforces.com/contest/913/problem/A (1)
http://mirror.codeforces.com/contest/912/problem/A (2) //Easy [corner-cases]
http://mirror.codeforces.com/contest/146/problem/A (1)
http://www.spoj.com/problems/ESYR/ (1) //Bad one :/
http://mirror.codeforces.com/contest/908/problem/A (1)
http://mirror.codeforces.com/contest/147/problem/A (2) //Parsing
http://mirror.codeforces.com/contest/139/problem/A (1)
http://mirror.codeforces.com/contest/137/problem/A (1)
7886 — Assigning Teams (2) //[EASY][SORTING]
http://mirror.codeforces.com/contest/133/problem/A (1)
http://mirror.codeforces.com/contest/134/problem/A (1)
http://mirror.codeforces.com/contest/131/problem/A (1)
http://mirror.codeforces.com/contest/127/problem/B (1) [EASY]
http://mirror.codeforces.com/contest/899/problem/B (2) //Dates
http://mirror.codeforces.com/contest/898/problem/C (3) //No thinking — just implementation
6157 How do spiders walk on water? (4) //boring problem
http://mirror.codeforces.com/contest/900/problem/A (1)
7613 Relative atomic mass (1)
http://mirror.codeforces.com/contest/122/problem/A (1) //Find all lucky
http://mirror.codeforces.com/contest/120/problem/B (1) //Iteration
http://mirror.codeforces.com/contest/120/problem/A (1) //Iff/Logic
http://mirror.codeforces.com/contest/118/problem/B (2) //[PRINTING]
http://mirror.codeforces.com/contest/108/problem/A (1) //[EASY][PRINT][TIME]
http://mirror.codeforces.com/contest/106/problem/A (1) //Iff-party
http://mirror.codeforces.com/contest/890/problem/A (1) //if or perm
http://mirror.codeforces.com/contest/90/problem/B (2) //No idea — just cycles
http://mirror.codeforces.com/contest/75/problem/A (1) //conversion
http://mirror.codeforces.com/contest/884/problem/B (1) //Simple sum +N-1
http://mirror.codeforces.com/contest/48/problem/A (1) //Very easy [fe. perm]
http://mirror.codeforces.com/contest/51/my (2) //Lex-lowest-string (|s|=4)
http://mirror.codeforces.com/contest/54/problem/A (2) //Single sweep
http://mirror.codeforces.com/contest/719/problem/C 3
http://mirror.codeforces.com/contest/747/problem/E 4
http://mirror.codeforces.com/contest/754/problem/C 5
11482 UVA (4)
11291 UVA (3)
11070 UVA (5) //evaluation of expression
11074 UVA (2)
http://mirror.codeforces.com/contest/678/problem/B 2 //calendar days
http://mirror.codeforces.com/contest/643/problem/A 3 //easy — just simulate
http://mirror.codeforces.com/contest/770/problem/D 5 //easy — but pain — draw
http://mirror.codeforces.com/contest/789/problem/B 3 //simulate (mby twice)
13171 UVA (1)
10800 UVA (3)
http://mirror.codeforces.com/contest/828/problem/B 2 //EASY & NICE — just analysis
http://mirror.codeforces.com/contest/825/problem/B 2 //EASY & NICE — Piskvorky — pro prvaky
http://mirror.codeforces.com/contest/837/problem/B 2 //Just implementation
http://mirror.codeforces.com/contest/837/problem/C 2 //Some nasty iffs
http://mirror.codeforces.com/contest/845/problem/B 2 //Easy pro prvaky
http://mirror.codeforces.com/contest/845/problem/D 3 //Iffs — folow the rules
http://www.spoj.com/problems/UNIHW/ 4 //NICE (but many iffs)
http://mirror.codeforces.com/contest/5/problem/A (2) //Parsing
http://mirror.codeforces.com/contest/5/problem/B (3) //Output formating
http://mirror.codeforces.com/contest/6/problem/B (2) //Simply check by adjancecy vector + set
http://mirror.codeforces.com/contest/7/problem/A (1) //Oneinteresting if
http://mirror.codeforces.com/contest/8/problem/B (2) //Sample vectors + set/or/array
http://mirror.codeforces.com/contest/12/problem/A (1) //Find mirror by middle
http://mirror.codeforces.com/contest/16/problem/A (1) //Easy check of chars
http://mirror.codeforces.com/contest/21/problem/A (2) //Easy but nasty iff imple
http://mirror.codeforces.com/contest/31/problem/B (2) //Boring imple
http://mirror.codeforces.com/contest/34/problem/C (3) //Easy string parsing
http://mirror.codeforces.com/contest/41/problem/C (2) //String parsing
http://www.spoj.com/problems/KPRIMESB/ (4)
http://www.spoj.com/problems/IITKWPCH/ (4) //NICE — on bits
http://www.spoj.com/problems/SUBSET/ (5) //VERY NICE — 3^10 (^2 but not exactly) (+ sorting)
https://www.hackerearth.com/practice/algorithms/dynamic-programming/bit-masking/practice-problems/algorithm/special-pairs-7/description/ (4) //NICE [Brute-force]
http://mirror.codeforces.com/contest/897/problem/D (4) //NICE! Back/Front
http://mirror.codeforces.com/contest/727/problem/C (2)
http://mirror.codeforces.com/contest/810/problem/D (4) //BS * 3 (same)
http://mirror.codeforces.com/contest/811/problem/D (4) //BFS — easy .. some ifs
http://mirror.codeforces.com/contest/835/problem/E (4) //NICE! Bitsets + Detect + XOR
http://mirror.codeforces.com/contest/844/problem/D (5) //NICE! Randomized algo
http://mirror.codeforces.com/contest/862/problem/D (4) //NICE! Find first + Binary Search
http://mirror.codeforces.com/contest/872/problem/D (4) //NICE! [no clue why it passed]
https://www.urionlinejudge.com.br/judge/en/problems/view/2652 (4) //Tree isomorphism
UVA 12489 //Tree
https://www.hackerrank.com/contests/hourrank-16/challenges/jenny-subtrees/problem
http://www.spoj.com/problems/DSUBTREE/ (5) //Isomorphism on trees (try all subsets)
http://www.spoj.com/problems/TREEISO/ (4) //Simple isomorphism of trees
http://mirror.codeforces.com/gym/101864 A //Observation
UVA 151
UVA 1394
UVA 440
3803 [LA]
https://www.urionlinejudge.com.br/judge/en/problems/view/1030
UVA 12912
UVA 13114
11351 UVA (2)
http://www.spoj.com/problems/CLSLDR/ (4) //Muchas queries — go DP
http://www.spoj.com/problems/WTK/ (Easy) Suggested by codeforrest
http://www.spoj.com/problems/DANGER/ (Easy) Suggested by codeforrest
http://www.spoj.com/problems/POCRI/ (Medium) Suggested by codeforrest
http://www.spoj.com/problems/NG0FRCTN/ (Medium) Suggested by codeforrest
http://www.spoj.com/problems/ADAPET/
UVA 12604
UVA 12467
UVA 11019
http://www.spoj.com/problems/NAJPF/ (4) //classical kmp — all patterns
http://mirror.codeforces.com/contest/808/problem/G (6) //with DP -harder
http://www.spoj.com/problems/ADAAPPLE/ [HLD][LCT works too]
http://www.spoj.com/problems/ADAVISIT/ [HLD]
http://www.spoj.com/problems/ADALICI/ [KTH Ancestor — FAST!]
http://www.spoj.com/problems/ADAORANG/
https://www.spoj.com/problems/COWGATH/ (5) //[VERY NICE][EULER][OFFLINE][SEGMENT]
https://mirror.codeforces.com/gym/102021 A //[IMPLEMENTATION][LCA]
http://mirror.codeforces.com/gym/101908/problem/L (5) //[NICE][HLD][FW]
http://mirror.codeforces.com/gym/101808/problem/K (5) //[NICE][IMPLEMENTATION][CYCLE]
http://www.spoj.com/problems/LCA/ //Easiest one — low constraints [practice]
http://www.spoj.com/problems/LCASQ/
http://mirror.codeforces.com/contest/916/problem/E (6) //[VERY NICE][SEG-TREE]//REROOT
http://mirror.codeforces.com/contest/911/problem/F (5) //[VERY NICE][LONGEST PATH]
https://devskill.com/CodingProblems/ViewProblem/141
UVA 12655
https://www.codechef.com/problems/PSHTTR
LightOJ 1162
Gym 100685G [2012-2013 ACM-ICPC, NEERC, Moscow Subregional Contest]
UVA 12533
https://www.codechef.com/problems/CLOSEFAR //But kinda more comples [ST]
http://mirror.codeforces.com/contest/733/problem/F 7
11354 UVA (4)
http://www.spoj.com/problems/POLICEMEN/ (3) //simple + small graph
http://www.spoj.com/problems/QTREE2/ (5) //very easy if bin. understrood
http://mirror.codeforces.com/contest/828/problem/F 7 // Differently MST / Outside
http://mirror.codeforces.com/contest/832/problem/D (5) //Classical + Depth /OR/ HLD +ST
http://www.spoj.com/problems/DRTREE/ (5) //NICE [finding ancestor + depths]
http://mirror.codeforces.com/problemset/problem/838/B (6) //VERY NICE [HLD + ET + ST]
http://www.spoj.com/problems/NTICKETS/ (4) //Maximum on path
http://www.spoj.com/problems/GRASSPLA/ (5) //HLD
http://mirror.codeforces.com/contest/855/problem/D (4) //VERY VERY BAD STATEMENT (not so bad problem)
http://mirror.codeforces.com/gym/101630 {L}(6) //[NICE][HLD or DSU][XOR] //Parenthessis
http://www.spoj.com/problems/ADASEED/ [HUNT]
http://www.spoj.com/problems/MC/
UVA 10192
UVA 531
LightOJ 1110
UVA 12747 //Perm
http://www.spoj.com/problems/XMEN/ //Perm
UVA 10405
UVA 12511 //Increasing
UVA 10635 //Increasing
10949 UVA (6) — Hunt or Bit
http://www.spoj.com/problems/MC/ (3) //Classical
http://www.spoj.com/problems/LCS0/ (7) //Bit
http://www.spoj.com/problems/ADAROADS/ [ONLINE][UPDATES][LCT]
http://www.spoj.com/problems/DYNALCA/en/ //DYNAMIC LCA
http://mirror.codeforces.com/gym/100460/problem/C
http://mirror.codeforces.com/gym/100960/problem/H
http://www.spoj.com/problems/DYNACON1/
http://mirror.codeforces.com/contest/892/problem/E (7) [VERY NICE]//By prices .. LCT
UVA 231
UVA 10131
2931 LA
http://www.spoj.com/problems/NDS/
UVA 481
http://www.spoj.com/problems/ELIS/
UVA 497
UVA 11790
http://www.spoj.com/problems/ALTSEQ/ 3 //solvable by FW in Nlog(N)
http://www.spoj.com/problems/VISIBLEBOX/ (4) //with multiset
http://www.spoj.com/problems/DOSA/ (5)
http://www.spoj.com/problems/CODERE3/ 3 //Low bounds LIS/LDS
http://www.spoj.com/problems/BRDGHRD/ 4 //lis (nondecreasing)
http://www.spoj.com/problems/GONESORT/ 4 //Permutation-lis + riddle statement
http://mirror.codeforces.com/contest/847/problem/B 4 //Multiple Lis's
http://mirror.codeforces.com/contest/67/problem/D (4) //[NICE][DOUBLE REMAP]
http://www.spoj.com/problems/ADAPATH/
http://www.spoj.com/problems/ADACITY/
http://www.spoj.com/problems/ADAPLNTS/
https://mirror.codeforces.com/contest/1198/problem/E (7) //[VERY NICE][HARD][KONIG][OBSERVATION]
URI 1330 (4) //[NICE][SIMPLE]
http://mirror.codeforces.com/gym/101873 F
http://mirror.codeforces.com/gym/101666 E //[NICE][GEOMETRY][BINARY SEARCH][PROBABILITY]
http://www.spoj.com/problems/MATCHING/ //Raw (no sauce)
http://mirror.codeforces.com/contest/116/problem/B (3) //Low cons. Can be done without algo
6234 — Tile Cut (LA)
10080 — Gopher II (UVA) //Easy — sympathic
11419 — SAM I AM (UVA) //Grid-Matching
http://mirror.codeforces.com/gym/101485 (Elementary Math — E) //Very nice principal [not that hard]
3673 — Black-White Grid (UVA) //Grid
12927 — Points Cover (UVA)
6851 — The Programmers (LA)
6887 — Book Club //NICE
6571 — It Can Be Arranged
12530 — Game of Tiles
http://mirror.codeforces.com/gym/100820 (Airport — A) //Nice one
http://mirror.codeforces.com/gym/100753 (Bounty Hunterr II — B) //VERY NICE — I refered multiple times to this principal
http://mirror.codeforces.com/gym/101408 (Cat vs Dog — C)
1171 — Knights in Chessboard (II) (LOJ) //Classical chess
12644 — Vocabulary
http://mirror.codeforces.com/gym/101047/problem/H
http://mirror.codeforces.com/problemset/problem/659/E
12972 — Cuban Challenge (UVA)
1201 — Taxi Cab Scheme (UVA)
12963 — Astragalus Nitidiflorus
6525 — Attacking rooks (LA)
3415 — Guardian of Decency (LA)
12159 — Gun Fight (UVA)
https://www.codechef.com/problems/CHEFYODA //Imho matching is not the crucial part here
12831 — Bob the Builder
http://mirror.codeforces.com/problemset/problem/831/D
11262 — Weird Fence
12549 — Sentry Robots
11138 — Nuts and Bolts
http://mirror.codeforces.com/contest/727/problem/D 4
11985 UVA (5)
http://www.spoj.com/problems/AMR12A/ (5) //VERY NICE goophers + bonus
http://www.spoj.com/problems/NITT4/ (4) //VERY NICE [Chessboard matching]
http://www.spoj.com/problems/SCPC11H/ (4)//NICE — Match those which fits inside
12045 UVA (4)
http://www.spoj.com/problems/ADAMONEY/
UVA 13298 — A Fibonacci Family Formula (4) //[NICE][CLASSICAL]
http://mirror.codeforces.com/gym/101628/problem/I (4) //[MODULAR][NICE][TRANSITION]
http://mirror.codeforces.com/gym/101845/problem/A
13284 Macarons (4) //[NICE][BITMASK][DP] Classical
http://mirror.codeforces.com/contest/147/problem/B (5) //[NICE][BS][GRAPHS]
http://mirror.codeforces.com/contest/107/problem/D (5) //[NICE][DP]
UVA 12653
LightOJ 1131
UVA — 12470
http://mirror.codeforces.com/problemset/problem/696/D
https://www.hackerrank.com/contests/mathemagic-bits/challenges/gp-on-fibonacci-matrix [accesable?]
https://www.hackerrank.com/contests/mathemagic-bits/challenges/degree-diameter-on-trees [accesable?]
LightOJ 1052
https://www.codechef.com/problems/KBIGNUMB
LightOJ 1160
LightOJ 1096
UVA 11486
http://mirror.codeforces.com/problemset/problem/718/C
LightOJ 1070
LightOJ 1132
http://mirror.codeforces.com/problemset/problem/621/E
Project Euler #114: Counting block combinations I
http://mirror.codeforces.com/problemset/problem/821/E
UVA 12593
https://www.codechef.com/AUG16/problems/SHAIKHGN //Not exactly but similar principle
11551 UVA (4)
11486 UVA (5)
10743 UVA (5) //A001169 [easy multi / hard to come with recurence]
http://mirror.codeforces.com/contest/821/problem/E (6) //Not trivial to come-up with matrix
http://www.spoj.com/problems/DCEPCA06/ (4) //NICE — 10x10 matrix
http://www.spoj.com/problems/GSWORDS/ (3) //NICE&EASY — 3-states "OO,OX,XO"
http://www.spoj.com/problems/TETRAHRD/ (4) //Easy + Sum
http://www.spoj.com/problems/NACCI/ (4) //Classical (N-Bonacci)
http://www.spoj.com/problems/JZPCIR/ (5) //VERY NICE: A137726
http://www.spoj.com/problems/ADAGROW/
http://www.spoj.com/problems/ADAFEAR/
https://www.urionlinejudge.com.br/judge/en/problems/view/1617 (4) //[BASIC]
13288 — Cordon Bleu (6) //[NICE][MATCHING]
http://mirror.codeforces.com/gym/100800 (Aqueduct Construction — A)
10806 — Dijkstra, Dijkstra.
12944 — Earthquake Disaster
12891 — Risk of Trading
https://www.codechef.com/problems/HOGON
http://mirror.codeforces.com/contest/863/problem/F (5) //VERY NICE
11613 UVA (6)
http://mirror.codeforces.com/contest/802/problem/C (8) //Nice but hard to see + negative
http://mirror.codeforces.com/contest/802/problem/N (5) //Easy but faster MCMF needed
http://mirror.codeforces.com/contest/818/problem/G (6) //NICE + MUCH Faster MCMF
http://www.spoj.com/problems/BNMT/ (7) //VERY NICE (some optimalisations needed + weird data set)
http://mirror.codeforces.com/contest/884/problem/F (6) //Alphabetical buckets
http://mirror.codeforces.com/contest/713/problem/C 7
http://www.spoj.com/problems/RMID2/ 4
http://www.spoj.com/problems/RMID/ 3 (as above just not so dynamic)
http://www.spoj.com/problems/EC_ESTA/ 4 //classical dynamic median
http://www.spoj.com/problems/DCEPCA09/ (6) //VERY NICE [MO +++ MEDIAN, MEAN, FREQ]
http://mirror.codeforces.com/contest/912/problem/E (5) //[VERY NICE][BS][2P][PRIMES]
http://mirror.codeforces.com/contest/888/problem/E (4) //NICE[EASY]
http://mirror.codeforces.com/contest/51/problem/E (6) //NICE[GRAPH][Cycles of length 5]
https://devskill.com/CodingProblems/ViewProblem/245
https://devskill.com/CodingProblems/ViewProblem/256
11851 UVA (5)
11465 UVA (5)
13207 UVA (4) //Straight-forward MIM
http://www.spoj.com/problems/COLOR_CC/ (4) //VERY NICE — div by partity (take lesser) → 8^6
http://www.spoj.com/problems/ADAUNIQ/ [Updates]
http://www.spoj.com/problems/ADANUM/
http://www.spoj.com/problems/ADAPEAR/
http://www.spoj.com/problems/ADAPHONE/
https://www.spoj.com/problems/MOZHSLS/ (5) //[VERY NICE]
http://www.spoj.com/problems/ADAFTBLL/ [Tree][Updates]
http://mirror.codeforces.com/gym/101879/problem/H (5) //[NICE][CLASSICAL][FREQUENCIES][FENWICK][BS]
http://www.spoj.com/problems/FREQUENT/
http://mirror.codeforces.com/contest/86/problem/D (4) //[NICE][CLASSICAL]
http://mirror.codeforces.com/contest/877/problem/F (6) //[NICE][NORMALIZE]
http://mirror.codeforces.com/problemset/problem/687/D
http://mirror.codeforces.com/problemset/problem/617/E
http://www.spoj.com/problems/DCEPCA09/
http://www.spoj.com/problems/COT2/
https://www.codechef.com/problems/DISTNUM3 //Tree + Update
https://toph.ws/p/distinct-dishting //Not sure if still working??
https://www.codechef.com/problems/CHEFNUMK
https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy-1/description/
http://www.spoj.com/problems/COT/ (7) //ON TREE [but very tight TLE]
http://www.spoj.com/problems/GOT/ (5) //ON TREE
http://www.spoj.com/problems/CPAIR2/ (4) //MO + Fenwick [VERY NICE]
http://www.spoj.com/problems/HRSIAM/ (5) //With updates
http://www.spoj.com/problems/KDOMINO/ (4) //NICE — Frequencies
https://mirror.codeforces.com/contest/1187/problem/B (3) //[NICE]
13257 — License Plates UVA //Brute-Force 26^3 queries in O(1)
http://mirror.codeforces.com/contest/92/problem/C (3) //[VERY NICE]
LightOJ 1157
https://www.codechef.com/problems/ASTRING
http://www.spoj.com/problems/MAIN8_E/
http://mirror.codeforces.com/problemset/problem/701/C
http://www.spoj.com/problems/STRSEQ/ //+DP
http://mirror.codeforces.com/problemset/problem/762/C
http://mirror.codeforces.com/problemset/problem/724/D
http://www.spoj.com/problems/SUBSN/ //+BS
https://www.hackerrank.com/contests/world-codesprint-5/challenges/short-palindrome //+DP
http://www.spoj.com/problems/ADACROW
http://www.spoj.com/problems/ADAPARTY/
http://www.spoj.com/problems/ADAPARTI/
http://mirror.codeforces.com/gym/101908/problem/J (6) //[VERY NICE][STEINER][GEOMETRY]
http://mirror.codeforces.com/gym/101666 G //[NICE][BURTE FORCE][OBSERVATION][SUBSETS]
http://mirror.codeforces.com/contest/907/problem/E (5) //[VERY NICE][CLIQUE][DP]
http://mirror.codeforces.com/contest/114/problem/B (3) //[CLIQUE][BRUTE-FORCE]
http://www.spoj.com/problems/JOHNNY/ //Not exact — points
http://www.spoj.com/problems/TAKIN/ (3) //[KNAPSACK][RECURSION]
http://mirror.codeforces.com/contest/839/problem/E (5) //NICE! Max-Clique
7743 — Cliques (Similar to ADAPARTI) (8) //Parametrisation
7616 Counting Cliques (4) //[NICE][CLIQUES][ELIMINATING-SETS]
https://mirror.codeforces.com/contest/1181/problem/A (2) //[EASY][FORMULA][MODULO]
https://www.spoj.com/problems/PRADIPSUM/ (2) //[EASY][FORMULA]
UVA 10667 //Largest rectangle
UVA 10074 //Largest rectangle
UVA 836 //Largest rectangle
UVA 1330 //Largest rectangle
12192 UVA 5
http://mirror.codeforces.com/contest/729/problem/B 2
http://mirror.codeforces.com/contest/710/problem/C 4
11871 UVA 6
11617 UVA (3)
11573 UVA (4)
11499 UVA (5)
11230 UVA (4)
http://www.spoj.com/problems/JOCHEF/ (5) //NICE: Lagers rectange 0/1 O(N*M)
http://www.spoj.com/problems/ADAGCD/ [+STL]
http://www.spoj.com/problems/ADAHACK/
http://www.spoj.com/problems/ADADUNG/
http://www.spoj.com/problems/ADACAROT/
http://www.spoj.com/problems/ADACON/
http://www.spoj.com/problems/ADATAXES/
http://www.spoj.com/problems/ADADIG/
http://www.spoj.com/problems/ADASETS/
https://mirror.codeforces.com/contest/1175/problem/A (2) //[EASY][SYMPATHIC][DIVISION]
https://mirror.codeforces.com/contest/1203/problem/C (3) //[NICE][GCD]
https://devskill.com/CodingProblems/ViewProblem/553 (3) //[VERY NICE][SIMPLE]
https://devskill.com/CodingProblems/ViewProblem/560 (2)
https://mirror.codeforces.com/contest/1176/problem/B (2) //[MODULO][GREEDY]
https://mirror.codeforces.com/contest/1200/problem/C (4) //[VERY NICE][GCD][LCM]
https://mirror.codeforces.com/contest/1182/problem/A (2) //[EASY][DP]
https://atcoder.jp/contests/abc136/tasks/abc136_b (2) //[IMPLEMENTATION][CONVERSION]
https://mirror.codeforces.com/contest/1185/problem/A (1)
https://mirror.codeforces.com/contest/1198/problem/F (6) //[VERY NICE][RANDOM][FACTORISATION][PRIME][GCD]
https://mirror.codeforces.com/contest/1183/problem/B (2) //[EASY][FORMULA][MIN/MAX]
https://mirror.codeforces.com/contest/1187/problem/A (1) //[EASY][FORMULA]
https://mirror.codeforces.com/contest/1195/problem/B (2) //[EASY][GAUSS][BRUTE]
https://mirror.codeforces.com/contest/1189/problem/E (5) //[INVERSION][STL]
https://www.spoj.com/problems/CANPR/ (5) //[NICE][MOBIUS] Weird TC (weak?)
https://www.spoj.com/problems/OVISLARSUM/ (3) //[FORMULA][128]
https://www.urionlinejudge.com.br/judge/en/problems/view/2876 (6) //[VERY NICE][GCD][IE]
https://mirror.codeforces.com/gym/102058/problem/E (3) //[BRUTE-FORCE][GCD]
https://mirror.codeforces.com/gym/101972/problem/A (3) //[EASY][SIMULATION]
https://toph.co/p/pascals-triangle (2)
https://toph.co/p/big-factorials (1)
https://www.codechef.com/viewsolution/21428053 (4) //[SORTING][ANGLES][MATH][COSINUS]
http://mirror.codeforces.com/gym/101962 C
http://mirror.codeforces.com/gym/101808/problem/G (4) //[GCD][IF][LCM]
http://mirror.codeforces.com/gym/101666 L //[GREED][DP] Logarithms
http://mirror.codeforces.com/gym/101666 C //[NICE][GCD]
13287 — Shattered Cake (2) //Rectangle
http://mirror.codeforces.com/gym/101650 G //Graphs
http://mirror.codeforces.com/contest/934/problem/D (4) //Polynomials
8253 — Boss Battle LA
http://mirror.codeforces.com/contest/919/problem/E (5) //[MODULAR-MATH]
http://mirror.codeforces.com/contest/149/problem/B (3) //Base to 10
http://mirror.codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)
http://mirror.codeforces.com/contest/148/problem/A (2) //[EASY][SIEVE][BRUTE-FOCE][LCM][IE]
http://www.spoj.com/problems/JGTLE/ (3) //Sum reduction
http://www.spoj.com/problems/BAPM/ (3) //Simple power / Observe, rare colisions
http://mirror.codeforces.com/contest/911/problem/C (2) //[Observation][Iff (or brute-froce)]
http://mirror.codeforces.com/contest/133/problem/B (2) //Bases + implementation
http://mirror.codeforces.com/contest/129/problem/A (1) //Parity
http://mirror.codeforces.com/contest/124/problem/D (4)
http://mirror.codeforces.com/contest/125/problem/A (1) //mod/div simple — if
http://mirror.codeforces.com/contest/902/problem/D (4) //Polynomials / Fibonacci / Bitset
http://mirror.codeforces.com/contest/899/problem/D (4) //X99999 possibilities
http://mirror.codeforces.com/contest/899/problem/C (3) //[NICE][GREEDY KNAPSACK]
http://mirror.codeforces.com/contest/899/problem/A (1)
http://mirror.codeforces.com/contest/898/problem/A (1)
http://mirror.codeforces.com/gym/101620 {F}(4) //[IFS][INVERSE][CASES]
http://mirror.codeforces.com/contest/900/problem/D (4) //[NICE][DIVISORS][GCD][IE]
http://mirror.codeforces.com/contest/900/problem/B (2) //Cycles or Brute-force + Division
http://mirror.codeforces.com/contest/119/problem/A (2) //[EASY][GCD]
8014 — Birthday Pizza Party (4) //[NICE][OVERFLOW][LCM WITH SHIFT]
7629 — Powers (3) //One path is factorisation
8037 — Military Service (2) //Sample formula
8085 — Divisors (4) //[NICE][PRIMES/FACTORISATION/SIEVE]
6589 — Captain Obvious and the Rabbit-Man (7) //Sylvester's formula
6582 — Magical GCD (4) //[NICE] — Data structures works too
8000 — FizzBuzz (1)
https://devskill.com/CodingProblems/ViewProblem/421 (2) //6 buckets
http://mirror.codeforces.com/contest/93/problem/E (5) //[VERY NICE][DP][RECURSION]
http://mirror.codeforces.com/contest/86/problem/A (3) //[NICE] 50* is best (unless more digits)
http://mirror.codeforces.com/contest/83/problem/D (5) //[VERY NICE][PRIMES][BRUTE-FORE-2]
http://mirror.codeforces.com/contest/82/problem/A (2) //Simulation
http://mirror.codeforces.com/contest/74/problem/C (4) //gcd
http://mirror.codeforces.com/contest/76/problem/E (4) //Divide sumations [BF]
http://mirror.codeforces.com/contest/71/problem/C (3) //[EASY][NICE][BRUTE-FORCE][DIVISORS]
http://mirror.codeforces.com/contest/70/problem/A (2) //3^(N-1)
http://mirror.codeforces.com/contest/43/problem/C (2) //Moduly by 3 {0/2+min(1,2)}
http://mirror.codeforces.com/contest/50/problem/A (1) //[EASY]
http://mirror.codeforces.com/contest/61/problem/C (4) //Base conversion + roman
UVA 355 //bases conversion
2559 [LA] //Base conversion
https://www.codechef.com/problems/COPRIME3 //Cyka Möbius
http://www.spoj.com/problems/PSTR/ //Cyka Möbius
http://mirror.codeforces.com/problemset/problem/803/F //Cyka Möbius
https://devskill.com/CodingProblems/ViewProblem/23
http://mirror.codeforces.com/contest/731/problem/F 4
12031 UVA (8)
http://mirror.codeforces.com/contest/722/problem/F (8)
http://mirror.codeforces.com/contest/716/problem/C 4
http://mirror.codeforces.com/contest/711/problem/E (8)
http://mirror.codeforces.com/contest/710/problem/D (6)
13154 (UVA) 7
13166 (UVA) 5
11962 (UVA) 2
11718 UVA 3
11510 UVA (5)
11538 UVA (3) //good one — just math
11556 UVA (1)
http://mirror.codeforces.com/contest/757/problem/E (8)
http://mirror.codeforces.com/contest/758/problem/F (7)
11481 UVA (4)
11237 UVA (4) //Nice — seems like knapsbag but it it not
11155 UVA (4) //Almost as previous problem
11038 UVA (3) //counting digits on interval
http://mirror.codeforces.com/contest/763/problem/C (7)
11087 UVA (4) //Sums of two numbers divisible with <=500 (10^5)
http://mirror.codeforces.com/contest/678/problem/C 2 //LCM
http://mirror.codeforces.com/problemset/problem/665/F (8) //p^3 | p*q
http://www.spoj.com/problems/LCMSUM/ //Vzorec v knihovničce
http://www.spoj.com/problems/FRNDZND/ (2) // (size 1 == 1, else 0)
http://www.spoj.com/problems/EXPOR/ //bit-by-bit (+ formula)
http://www.spoj.com/problems/FACTDIV/ (5) //dyn-update of ans/factors GOOD
http://www.spoj.com/problems/PAIRDIV/ (6) //cyka möbius -_-
http://www.spoj.com/problems/FCDC/ (4) //keep factorized factorial
http://www.spoj.com/problems/NTHPRIME/ (7) // BS + NumPrime GOOD!!
http://www.spoj.com/problems/DIVFACT3/ (7) // Sieve 10^8 + sqrt search
http://www.spoj.com/problems/DIVFACT4/ (8) // Prime count
http://mirror.codeforces.com/contest/776/problem/C (4) //segments div. by number
http://mirror.codeforces.com/contest/776/problem/E (6) //vypsat cisla: f(N)=Phi(N),g(N)=N
http://www.spoj.com/problems/PHT/ (2) //easy BS (NN+2N) mby math?
http://www.spoj.com/problems/GCDEX/ (7) //OEIS A006579 — enough [well imp]
http://www.spoj.com/problems/APS/ (3) //just sieve + generate
http://www.spoj.com/problems/WPC5I/ (3)//fc: C[a]!=C[b]:F[a]^max(C[a],C[b])
http://www.spoj.com/problems/SPEC_SET/ N→N/k→N/k/k
http://www.spoj.com/problems/DCEPC11B/ (5) //Wilson't theorem!
http://www.spoj.com/problems/FACTMULN/ (5) //each f[i]/c[i] separately
http://www.spoj.com/problems/SPCM/ (4) //just factorisation + prime check (10^12)
http://www.spoj.com/problems/TWOGAME/ (5) //gcd == Power of 3 => YES
http://www.spoj.com/problems/MKEQUAL/ (2) //Chceck if sum is divisible by N
http://www.spoj.com/problems/TIPTOP/ (3) //sqrt(N)==N? NICE!!
http://www.spoj.com/problems/PSYCHON/ (4) // fast factorisation
http://www.spoj.com/problems/ENIGMATH/ (1) // swap and div by gcd
http://www.spoj.com/problems/SNGPG/ (3) // prime gen + check
http://mirror.codeforces.com/contest/795/problem/A (2) //brute-force
http://mirror.codeforces.com/contest/801/problem/E (6) //NICE! — Clique-DAG + inversion
http://mirror.codeforces.com/contest/798/problem/C (4) //GCD == at the beginning OR 2
http://mirror.codeforces.com/contest/803/problem/C (3) //Only "low" K and just divisors
10830 (4) //simple add 2→ sqrt(N) + their mirrors
http://mirror.codeforces.com/contest/817/problem/A (2) //check division + parity
13209 UVA (3) //Simple simulation of division (+states rememberance)
http://mirror.codeforces.com/contest/834/problem/C (4) //Has cube-root + both num divisible by cuberoot
http://mirror.codeforces.com/contest/837/problem/E (5) //Factorisation + GCD attributes
http://www.spoj.com/problems/SUMMATION/ (3) //Number contribution: 2^(N-1)
http://www.spoj.com/problems/SECTORS/ (4) //Odd len OR sum of odd indices == sum of even
http://www.spoj.com/problems/IITKWPCM/ (6) //VERY NICE — Gauss's generalisation of Wilsons Theorem
http://www.spoj.com/problems/UCV2013A/ (4) //N*(N^L-1)/(N-1)
http://www.spoj.com/problems/KIMO1/ (4) //NICE — Adding/Subing by modulus
http://www.spoj.com/problems/AFS2/ (4) //Sum of divisort (sqrt(N)) — (+128int)
http://www.spoj.com/problems/FUNNUMS/ (4) //Permutations (get ith + guess ith)
http://www.spoj.com/problems/MAY99_3/ (3) //GCD
http://www.spoj.com/problems/PUCMM334/ (3) //Classical hats problem
http://www.spoj.com/problems/LCPC11B/ (4) //Factorize + count all subsets
http://www.spoj.com/problems/THREENUMBERS/ (2) //EASY & NICE [lcm]
http://www.spoj.com/problems/GAMES/ (2) //EASY&NICE — Go discrete (by 10^k) → 10^k/GCD
http://www.spoj.com/problems/SUBSHARD/ (4) //dig*10^sufix*(choose sufix)*^Prefix [VERY NICE]
http://www.spoj.com/problems/INVDIV/ (6) //Sum of divisors function + factorisation [NICE]
http://www.spoj.com/problems/JNEXT/ (2) //EASY — Zahřívačka pro prváky
http://www.spoj.com/problems/TSHOW1/ (3) //NICE — Almost as binary repre with 5/6
http://mirror.codeforces.com/contest/859/problem/B (2) //Easy by iteration
http://mirror.codeforces.com/contest/861/problem/A (2) //5,2 division [EASY]
http://www.spoj.com/problems/ABA12D/ (4) //NICE — Formula for sum divisors Prod(Sum(fac-powers))
http://www.spoj.com/problems/MAIN74/ (3) //Fibo's
http://www.spoj.com/problems/NOSQ/ (3) //Sieve + Digit check
http://www.spoj.com/problems/SQUAREV1/ (3) //NICE (but dumb code limit)
http://mirror.codeforces.com/contest/597/problem/A (1) //Simple if+2*Divide
http://www.spoj.com/problems/STREETR/ (3) //Easy [GCD]
http://www.spoj.com/problems/HPYNOSII/ (3) //<=1000 after first move
http://www.spoj.com/problems/HPYNOS/ (1) //Same as above — 1 number
http://www.spoj.com/problems/IITD4/ (3) //Brute-force [sieve-like]
http://www.spoj.com/problems/GIRLSNBS/ (2) //Some easy formula
http://www.spoj.com/problems/GUESSTHE/ (2) //NICE [EASY][LCM]
http://mirror.codeforces.com/contest/867/problem/B (2) //NICE [observation][1 2]
http://www.spoj.com/problems/NDIVPHI/ (4) //NICE — Multiple of lowest primes [BIG-INT]
http://www.spoj.com/problems/NDIVPHI2/ (5) //NICE — Same as above [bigger constraints]
http://mirror.codeforces.com/contest/6/problem/A (1) //Triangle check (4 pts)
http://mirror.codeforces.com/contest/869/problem/B (1) //Answer is usually 0
http://mirror.codeforces.com/contest/9/problem/C (2) //Bases (2→ 10)
http://mirror.codeforces.com/contest/20/problem/B (2) //Ax^2+Bx+C=0 (find roots)
http://mirror.codeforces.com/contest/27/problem/E (5) //[VERY NICE]: Factorisation+Recursion
http://mirror.codeforces.com/contest/32/problem/C (3) //DSU works too
http://mirror.codeforces.com/contest/872/problem/C (3) //NICE — Compose of 4 (mby one 6 or 9)
http://mirror.codeforces.com/contest/876/problem/B (3) //Group by modulo
http://www.spoj.com/problems/ADABANKET/ //Observation (but Stoer-Wagner works too)
https://mirror.codeforces.com/contest/1194/problem/A (1) //[TRIVIAL]
https://www.spoj.com/problems/ARRTWIST/ (3)
https://www.spoj.com/problems/OPMODULO/ (3) //[NICE]Brute-force and observe
https://mirror.codeforces.com/gym/102001/problem/I (2) //[PARITY]
https://mirror.codeforces.com/gym/102001/problem/A (4) //[VERY NICE][FREQUENCY]
https://mirror.codeforces.com/gym/101991/problem/L (3) //[NICE][EASY][BITS]
https://mirror.codeforces.com/gym/102021 F //[NICE][SEQENCE]
https://www.codechef.com/problems/BUDDYNIM (3) //[OBSERVATION][NICE]
http://mirror.codeforces.com/gym/101962/problem/H (4) //[SEQUENCES][SIMULATION]
http://mirror.codeforces.com/contest/922/problem/C (3) //Note that K is always very low
http://mirror.codeforces.com/contest/912/problem/B (2) //Bits/XOR
http://mirror.codeforces.com/contest/911/problem/D (3) //[VERY NICE]
http://mirror.codeforces.com/contest/902/problem/E (5) //[VERY NICE] //LCT works too
7589 Rearranging a Sequence (3) //Print from back and then real
http://mirror.codeforces.com/gym/101630 {A}(6) //[NICE][STL]
http://mirror.codeforces.com/contest/122/problem/B (1) //just 4 or 7
http://mirror.codeforces.com/contest/116/problem/E (6) //[NICE][COMBINATORICS][FIND ANY]
http://mirror.codeforces.com/contest/892/problem/D (4) //NICE [SORTING]
http://mirror.codeforces.com/contest/897/problem/E (5) //[NICE][SET] //2 will beat all
7730 To begin or not to begin (3) //Parity
http://mirror.codeforces.com/contest/122/problem/D (4) //[NICE] Sweep /OR/ cycle
http://mirror.codeforces.com/contest/128/problem/D (6) //Normalize + Sweeps
https://mirror.codeforces.com/gym/101981 G //A000332
https://mirror.codeforces.com/gym/102001/problem/C //De Bruine
6591 — Bus (2) //2^N-1
12004 UVA 2
11273 UVA 5 //https://oeis.org/A001088
11077 UVA 3 //https://oeis.org/A094638
http://www.spoj.com/problems/VECTAR5/ 3 //https://oeis.org/A038721
http://www.spoj.com/problems/ESYRCRTN/ 2 //generate and see
http://www.spoj.com/problems/IITWPC4B/ 3 //http://oeis.org/A005044
http://www.spoj.com/problems/POLCONST/ (4) //A003401+Fermat Number (Prime)
http://www.spoj.com/problems/CUTCAKE/ (3) // pattern [1 22 333 4444 55555]
10872 UVA 3 //Alcuin's Sequence
http://www.spoj.com/problems/LOVINGPW/ (3) //A000788
http://www.spoj.com/problems/CBANK/ (3) //A000292 Tetrahedral numbers
http://www.spoj.com/problems/GUMATH2/ (4) //A000240 Modulo by MOD*2
http://www.spoj.com/problems/MATHII/ (4) //A006218 (Two formulas => sqrt(N))
http://www.spoj.com/problems/KOPC12B/ (4) //A002457 (factorial + factorial modular)
http://www.spoj.com/problems/YUMMY/ (4) //A006534
http://www.spoj.com/problems/ADV04B1/ (5) //A001850
http://www.spoj.com/problems/FLWRS/ (4) //A002464
http://www.spoj.com/problems/RANJAN02/ (3) //A024023
http://www.spoj.com/problems/BOMARBLE/ (2) //A000326
http://mirror.codeforces.com/contest/57/problem/C (4) //A045992
http://mirror.codeforces.com/contest/918/problem/A (1) //Fibo
http://www.spoj.com/problems/ADARAIN/
http://www.spoj.com/problems/ADARAINB/
http://www.spoj.com/problems/ADAROBOT/
https://www.spoj.com/problems/CLFLARR/ (3) //[NICE][EASY][QUEUE][STL]
https://mirror.codeforces.com/gym/102021 M //[VERY NICE][SPANNING]//LCA WORKS TOO
http://mirror.codeforces.com/gym/101840 I //[NICE][PREPROCESS]
http://mirror.codeforces.com/problemset/problem/816/B //Easier ST
11266 UVA (6) //slightly knapsack || [NICE]
http://mirror.codeforces.com/contest/761/problem/F (7)
http://www.spoj.com/problems/UPDATEIT/ (2) //basic method
13189 UVA (4) //simulation + sort queries
http://www.spoj.com/problems/HAYBALE/ (3) //Basic sum + sort (segment tree would work too)
http://mirror.codeforces.com/gym/101597/problem/H (6) //Offline 2D sum + geometry
https://www.spoj.com/problems/JUSTAPAL/ (6) //[VERY NICE][SA][RMQ]
https://www.spoj.com/problems/DRAGKING/ (4) //[CLASSICAL][DP]
https://mirror.codeforces.com/gym/101981 (5) //[NICE][SEGMENT][MANACHER][ZETA][SA]
https://mirror.codeforces.com/gym/101972/problem/F (3) //[EASY][OBSERVATION][GREEDY]
http://mirror.codeforces.com/gym/101628/problem/E (4) //[NICE][DP] //Easy
http://mirror.codeforces.com/gym/101864 J //[NICE][MANACHER]
http://mirror.codeforces.com/gym/101806/problem/Q (4) //[HASHING][PALINDROMIC-TREE]
http://mirror.codeforces.com/contest/897/problem/B (2) //Palindromic numbers [EASY][FIRST]
http://mirror.codeforces.com/contest/883/problem/H (3) //Make as least odd as possible
http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_c (3) //Similar to remove-dp, but greedy
http://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_d (4) //DP with greedy thinking
http://mirror.codeforces.com/contest/59/problem/C (3) //Implementation [constructive]
UVA 13092 //manacher
http://www.spoj.com/problems/MSUBSTR/ //manacher
UVA 11888 //manacher
https://www.hackerrank.com/contests/101hack35/challenges/circular-palindromes //manacher
UVA 12378 //manacher
https://www.hackerrank.com/contests/world-codesprint-5/challenges/challenging-palindromes //SA
http://www.spoj.com/problems/NUMOFPAL/ //Palindromic Tree
http://mirror.codeforces.com/problemset/problem/245/H //# of palindromes [DP]
http://www.spoj.com/problems/ANAGR/ 2 //frequency + palindromes
http://www.spoj.com/problems/AMR12D/ (1) //Palindrome check //Zahrivacka pro prvaky
http://mirror.codeforces.com/problemset/problem/835/D //Hashing
http://mirror.codeforces.com/contest/137/problem/D (4) //[NICE][DP]
11019 UVA (5)
http://mirror.codeforces.com/contest/137/problem/B (1) //Frequency + size
http://mirror.codeforces.com/contest/136/problem/A (1) //Permutation cycles
http://mirror.codeforces.com/contest/844/problem/C 3 //NICE Permutations in array
http://mirror.codeforces.com/contest/48/problem/D (3) //NICE [frequency array]
http://mirror.codeforces.com/contest/56/problem/B (2) //Restore from 1 reverse [EASY]
http://mirror.codeforces.com/contest/122/problem/D (5) //NICE [BRUTE-FORCE]//ONLY BACK MATTERS
http://mirror.codeforces.com/contest/893/problem/F (6) //[VERY NICE][EULER TOUR]
http://mirror.codeforces.com/contest/813/problem/E (6) //Easy but hard data structure
https://mirror.codeforces.com/contest/893/problem/F //Suggested by phibrain
http://www.spoj.com/problems/ADAPLUS/
https://mirror.codeforces.com/contest/1175/problem/E (5) //[VERY NICE][LIFTING][PRIORITY]
https://mirror.codeforces.com/contest/1181/problem/C (4) //[VERY NICE][RMQ]
https://atcoder.jp/contests/abc136/tasks/abc136_d (4) //[NICE][PARITY]
https://mirror.codeforces.com/contest/1194/problem/B (3) //[IMPLEMENTATION][INDEXING]
http://www.spoj.com/problems/ADASQR/ [Monotone Queue]
https://toph.co/p/rio-and-inversion (5) //[NICE][INVERSIONS][PREFIX SUM][2D]
http://mirror.codeforces.com/gym/101801 I //[PREFIX SUM]
http://mirror.codeforces.com/gym/101889 L //[NICE][PREFIX SUM][BINARY SEARCH]
http://mirror.codeforces.com/contest/120/problem/D (3) //But maybe work naively ?!
http://mirror.codeforces.com/contest/48/problem/B (2) //2D Prefix Sum [BF prolly works too]
http://mirror.codeforces.com/problemset/problem/761/F
VA 10360 //2D Prefix Sum
UVA 983 //2D Prefix Sum
http://mirror.codeforces.com/contest/777/problem/C (4) //NICE
http://mirror.codeforces.com/contest/818/problem/C (4) //Prefix Sum
http://mirror.codeforces.com/contest/834/problem/B (2) //26 queries — NICE rozehrivacka pro prvaky
http://www.spoj.com/problems/RANGESUM/ (4) //NICE: Offline (delta) + Prefix Sum
http://www.spoj.com/problems/RANDG/ (3) //NICE [but too low bounds] [PrefixSum] [Try all indexes]
http://www.spoj.com/problems/HARSHAD/ (3) //Sieve + simple function
http://www.spoj.com/problems/PUCMM210/ (3) //Number theory (thinking not necessary)
http://www.spoj.com/problems/BCAKE/ (3) //Prefix sum of rectangle + N^4
http://www.spoj.com/problems/PAIRSUM/ (4) //VERY NICE — Prefix sum + Prefix PW sum
http://www.spoj.com/problems/MAIN111/ (3) //Sieve + Brute Force (answer in O(1))
http://www.spoj.com/problems/PLUSEVI/ (4) //NICE — There are not many of them
http://mirror.codeforces.com/contest/18/problem/C (2) //Prefix sum End==2*i
http://mirror.codeforces.com/contest/873/problem/B (2) //Search for same prefix (+/-1)
http://mirror.codeforces.com/contest/33/problem/C (4) //Prefix sum + Sweep from back + sweep from front
http://mirror.codeforces.com/contest/872/problem/B (3) //Sweep from both sides (RMQ works too)
http://www.spoj.com/problems/NTHPRIME/
http://www.spoj.com/problems/DIVFACT4/
http://mirror.codeforces.com/problemset/problem/665/F
https://www.codechef.com/problems/CNTPRIME
http://www.spoj.com/problems/SUMPRIM1/
http://www.spoj.com/problems/SUMPRIM2/ [NO — hard]
https://www.hackerrank.com/contests/projecteuler/challenges/euler010/problem //easy
http://www.spoj.com/problems/ADAGIFT/
https://www.spoj.com/problems/PRMFN/ (5) //[VERY NICE][GREEDY]
http://www.spoj.com/problems/PON/en/
http://www.spoj.com/problems/DAYOUT2C/en/ [EASY]
Project Euler #60: Prime pair sets
Project Euler #58: Spiral primes
Project Euler #131: Prime cube partnership
https://devskill.com/CodingProblems/ViewProblem/229
https://devskill.com/CodingProblems/ViewProblem/327
Gym 100753K [2015 German Collegiate Programming Contest (GCPC 15) + POI 10-T3]
Project Euler #130: Composites with prime repunit property
http://www.spoj.com/problems/ABA12A/ (3)
10871 UVA (3) //Easy — fermat not necessary
http://www.spoj.com/problems/POP1/ (4) //Fast primality testing (or somehow)
http://www.spoj.com/problems/POP2/ (5) //NICE — same as above (yet with ll)
http://www.spoj.com/problems/POP3/ (6) //same as above (yet with big)
http://www.spoj.com/problems/DCEPC203/ (6) //NICE [optimalisation]
http://www.spoj.com/problems/PRIMPERM/ (4) //NICE (next_perm + sieve)
https://mirror.codeforces.com/contest/1173/problem/E1 (5) //[NICE][DP]
https://mirror.codeforces.com/contest/1194/problem/F (6) //[NICE][COMBINATORICS][PREPROCESS]
http://mirror.codeforces.com/gym/101982 (5) K //[NICE][DP]
http://mirror.codeforces.com/gym/101845/problem/G (4) //[DP] Classical
http://mirror.codeforces.com/gym/101845/problem/M (3) //[NICE][OBSERVATION]
http://mirror.codeforces.com/gym/101726/problem/B (4) //[NICE][DP][BRUTE-FORCE]
https://www.devskill.com/CodingProblems/ViewProblem/470 (3) //Brute Force
8262 — Knockout Tournament (4) [LA] //[NICE][SIMULATION] //Might not be working on LA (but on CF y)
http://mirror.codeforces.com/contest/912/problem/D (4) //[VERY NICE][EXPECT][DIJKSTRA]
http://mirror.codeforces.com/contest/908/problem/D (5) //[DP][MATH][INVERSION]
7821 — Elections (4) //[EASY][DP]
http://mirror.codeforces.com/gym/101620 {G}(5) //[VERY NICE][DIJKSTRA][EXPECTED VALUE]
http://mirror.codeforces.com/contest/110/problem/D (4) //[NICE][COMBINATORICS]
http://mirror.codeforces.com/contest/108/problem/D (4) //[NICE][SIMPLE][COMBINATORICS]
7619 — Guessing the Dice Roll (5) //[NICE][AHO][MATRIX EXPO]
7998 — Election (3) //Math works too [probability][DP]
LightOJ 1104 //Birthday Paradox
Gym 101064K [2016 USP Try-outs] //Birthday Paradox
11762 UVA (5)
11427 UVA (5)
11348 UVA (2)
http://mirror.codeforces.com/contest/768/problem/D (4) //With DP
http://www.spoj.com/problems/IITWPC4J/ (4) //with DP
10828 UVA (5) //Nice problem but bad statemend: Expected value of visits MC
10777 UVA (4) //NICE — yet solvable with DP
http://mirror.codeforces.com/contest/839/problem/C (3) //NICE & Easy => Tree
http://www.spoj.com/problems/ZCR/ (3) //Easy (+DP)
http://www.spoj.com/problems/IITKWPCN/ (2) //Easy — Odd/Eve (black balls)
http://mirror.codeforces.com/contest/846/problem/F (5) // Expected number of unique elements
http://www.spoj.com/problems/BTCODE_H/ (4) //DP (but main GROW is idea)
http://mirror.codeforces.com/contest/867/problem/D (5) //VERY NICE [DP]
http://mirror.codeforces.com/contest/24/problem/D (5) //VERY NICE [DP]+[TIME]
http://mirror.codeforces.com/contest/28/problem/C (4) //VERY NICE [DP]
https://mirror.codeforces.com/contest/1175/problem/B (3) //[STACK]
https://www.codechef.com/problems/HPIRATES (4) //[VERY NICE][OBSERVATION][GRAPHS]
8255 — Dunglish LA //Finding all possibilities
http://mirror.codeforces.com/contest/915/problem/C (4) //[NICE][DP-works-too][GREEDY]
http://mirror.codeforces.com/contest/134/problem/B (4) //Number Theory
http://mirror.codeforces.com/contest/897/problem/C (4) //+Slightly [DP]
6585 — Draughts (4) //[NICE][BACKTRACK][DFS]
http://mirror.codeforces.com/contest/68/problem/D (5) //[NICE] Keep max and kill branches
UVA 536 //Tree from dfs
UVA 12347 //BST from preorder
http://www.spoj.com/problems/GOC11A/ 4
13170 UVA (7) //heavy implementation — but NICE!
10854 UVA (3) //if/else
http://mirror.codeforces.com/contest/31/problem/D (4) //[NICE] Brute-force by recursion
http://mirror.codeforces.com/contest/36/problem/B (2) //[NICE][SIMPLE]
https://www.spoj.com/problems/MOZPWS/ (4) //[NICE][IMPLEMENTATION][MQ]
https://mirror.codeforces.com/gym/101972/problem/G (4) //[NICE][SWEEP WORKS TOO]
http://mirror.codeforces.com/problemset/problem/514/D //+BS
http://mirror.codeforces.com/problemset/problem/872/B
http://www.spoj.com/problems/TNVFC1M/
https://devskill.com/CodingProblems/ViewProblem/19
http://mirror.codeforces.com/contest/713/problem/D 6
http://mirror.codeforces.com/contest/675/problem/E 5
http://www.spoj.com/problems/POSTERIN/ 5 //VERY NICE — Delete all minimas
http://www.spoj.com/problems/RPLN/ (3) //RMQ only
http://www.spoj.com/problems/CITY2/ (4) //RMQ + MAP [NICE][VAGUE STATEMENT]
http://www.spoj.com/problems/DIFERENC/ (4) //Solve separately (linear D&C)
http://mirror.codeforces.com/contest/863/problem/E (4) //OR some Queue / sorting
http://mirror.codeforces.com/contest/5/problem/C (4) //NICE — many other options
http://mirror.codeforces.com/contest/15/problem/D (5) //VERY NICE 2D RM [sliding-windw][monotone-queue]
http://mirror.codeforces.com/contest/873/problem/E (5) //[NICE][Brute-Force + RMQ]
http://www.spoj.com/problems/AROPE/ 4
http://www.spoj.com/problems/AROPE2/ 5 //same as above (+time)
http://www.spoj.com/problems/ADAPANEL/ [combinatorics]
13301 — Impossible Communication (4) //[CUTE][SAMPLE][OBSERVATION][EASY]
http://mirror.codeforces.com/problemset/problem/427/C proposed by unofficial10
http://mirror.codeforces.com/contest/894/problem/E (5) //[NICE][DP]
https://devskill.com/CodingProblems/ViewProblem/79
UVA 11838
UVA 247
UVA 13057
UVA 12645
UVA 11770
UVA 12926
UVA 11324
UVA 11709
UVA 12745
http://www.spoj.com/problems/TFRIENDS/ (4) //just scc size
http://www.spoj.com/problems/CAPCITY/ (4) //scc destination [WEAK TC]
http://mirror.codeforces.com/contest/22/problem/E (5) //[NICE][make it strongly connected][SRC>DST]
http://www.spoj.com/problems/ADABERRY/ [+TREAP]
https://mirror.codeforces.com/contest/1180/problem/E (6) //[VERY NICE]
https://mirror.codeforces.com/contest/1187/problem/D (5) //[VERY NICE][GREEDY][STACK]
https://toph.co/p/maintain-the-queue (5) //[NICE][QUEUE]
http://mirror.codeforces.com/gym/101992/problem/L (5) //[VERY NICE]
http://mirror.codeforces.com/gym/101982 F //[SWEEP][NORMALIZE][NICE][XOR]
http://mirror.codeforces.com/gym/101962/problem/I (4) //[BS]
http://mirror.codeforces.com/gym/101801 G //Two ST [SEQUENCE]
http://mirror.codeforces.com/gym/101879/problem/G (5) //Merge / Special
http://mirror.codeforces.com/gym/101741/problem/J (6) //[NICE][COMBINATORICS]
http://mirror.codeforces.com/contest/914/problem/D (5) //[NICE][GCD][LOG]
http://mirror.codeforces.com/contest/915/problem/E (5) //[VERY NICE][UNLIMITED]
http://mirror.codeforces.com/contest/145/problem/E (5) //[NICE]//Bit swap + subsequence
http://www.spoj.com/problems/ADAGF/
http://www.spoj.com/problems/ADATREE/
http://mirror.codeforces.com/contest/911/problem/G (7) //Segment tree over queries
http://mirror.codeforces.com/contest/895/problem/E (5) //[PRECISION]
http://mirror.codeforces.com/contest/52/problem/C (4) //Easy [MIN]+[INCREASE]
http://mirror.codeforces.com/contest/56/problem/E (5) //[NICE][NORMALIZE][MAX]
http://mirror.codeforces.com/contest/877/problem/E (5) //[VERY NICE][EULER TOUR TREE]
https://devskill.com/CodingProblems/ViewProblem/283
https://devskill.com/CodingProblems/ViewProblem/315
http://mirror.codeforces.com/problemset/problem/756/C
http://mirror.codeforces.com/contest/739/problem/C (8)
http://mirror.codeforces.com/contest/718/problem/C (8)
http://mirror.codeforces.com/contest/750/problem/E (7)
http://mirror.codeforces.com/contest/759/problem/C (7)
11165 UVA (5)
http://mirror.codeforces.com/contest/763/problem/E (8) //VERY NICE — [non-trivial]
http://www.spoj.com/problems/BGSHOOT/ (5) //normalize — then easy
http://www.spoj.com/problems/KGSS/ (4)
http://mirror.codeforces.com/contest/765/problem/F (7) //VERY NICE — CASCADE
http://www.spoj.com/problems/GSS1/ (5) //Idea — then easy
http://www.spoj.com/problems/KQUERYO/ (5) //Seg-tree of vectors
http://mirror.codeforces.com/contest/633/problem/G (8) //EulerTree+Seg+Bitset
http://www.spoj.com/problems/NAJ0001/ (7) //10^8 int — memory (and worked)
http://www.spoj.com/problems/PRMQUER/ (5) //2 segment trees + sieve
http://www.spoj.com/problems/EC_DIVS/ (5) //dunno if intended
http://www.spoj.com/problems/DCEPC11I/ (5) //NICE — 1,2,3,4,5,.. inc
http://www.spoj.com/problems/QUE2/ (4) //kth number
http://mirror.codeforces.com/contest/785/problem/E (6) //Seg+Treap [and faster]
http://mirror.codeforces.com/contest/786/problem/B (6) //+Dijkstra
13183 UVA (6) //Merge-Sort-Tree [dunno]
http://mirror.codeforces.com/contest/121/problem/E (7) //Dunno — done by vectorisation
http://mirror.codeforces.com/contest/803/problem/G (5) //VERY NICE!! — ST 10^9 + ST/RMQ 10^5
http://mirror.codeforces.com/contest/794/problem/F (7) //Digit by digit! (N*log(N)*100 )
http://mirror.codeforces.com/contest/811/problem/E (6) //VERY NICE — DSU (easier Timofey + animals)
http://mirror.codeforces.com/contest/817/problem/F (7) //10^18 + MEX ~~ NICE yet problematic
http://mirror.codeforces.com/contest/816/problem/B (3) //Or offline trick makes it easier
http://mirror.codeforces.com/contest/834/problem/D (5) //+Dynamic Programming | NICE
http://www.spoj.com/problems/SBO/ (5) //preLast→ last (-1), last→ now (+1) — VERY NICE
http://www.spoj.com/problems/GOODE/ (5) //NICE: Inversion + L-Mex
http://www.spoj.com/problems/CNTPRIME/ (3) //ST+Sieve (short range)
http://www.spoj.com/problems/SEGSQRSS/ (4) //NICE {weak data} ~~ SQRT works too
http://www.spoj.com/problems/MON2012/ (5) //NICE [Online][10^9 Range]
http://www.spoj.com/problems/PARSUMS/ (4) //But other approaches work too
http://www.spoj.com/problems/THRBL/ (4) //Simple SA — maximum on range <= A[a]
http://www.spoj.com/problems/HORRIBLE/ (3) //Totally classical
http://www.spoj.com/problems/MULTQ3/ (4) //NICE (interesting operation)
http://www.spoj.com/problems/PERMPATT/ (4) //NICE [minimum][+IDEA]
http://mirror.codeforces.com/contest/869/problem/E (5) //NICE — 2D [random][XOR]
http://mirror.codeforces.com/contest/19/problem/D (5) //NICE [+BS][+SET] {bs not necessary}
11885 UVA 7 //Previous problem requested for statement
11522 UVA 3 //Trick — low numbers only :P
http://www.spoj.com/problems/ADAPRIME/
https://devskill.com/CodingProblems/ViewProblem/577 (4) //[NICE][TWO POINTERS]
https://www.spoj.com/problems/EVENSEMIP/ (5) //[VERY NICE][SEGMENTED]
http://mirror.codeforces.com/gym/101982 H //[GOLDBACH]
http://mirror.codeforces.com/contest/114/problem/E (5) //[NICE][FAST THINGS NEEDED][SEGMENTED]
http://mirror.codeforces.com/contest/58/problem/B (3) //[NICE][GREEDY][LEAST PRIME FACTOR]
Project Euler #134: Prime pair connection //Segmented
11610 UVA (5)
11353 UVA (3)
http://www.spoj.com/problems/TDPRIMES/ (4)
http://www.spoj.com/problems/VECTAR8/ (3)
http://www.spoj.com/problems/NFACTOR/ (4)
http://www.spoj.com/problems/HS08PAUL/ (4) //simply generate
http://mirror.codeforces.com/contest/776/problem/B (3) //Easy — trict: PM-1/ELSE-2
http://www.spoj.com/problems/GGD/ (4) // N/lowestDiv*(lowestDiv-1)
http://mirror.codeforces.com/contest/822/problem/D (4) //DP + Lowest factor
http://www.spoj.com/problems/NGIRL/ (4) //Squares — Primes + BS == Easiest
http://www.spoj.com/problems/PTRI/ (5) //Very fast sieve necessary:/
http://www.spoj.com/problems/AFS/ (3) //Sum of divisort + DP
http://www.spoj.com/problems/BSPRIME/ (4) //Very fast sieve needed
http://www.spoj.com/problems/DCEPC505/ (4) //NICE — at most 10527450
http://www.spoj.com/problems/CUBEFR/ (3) //NICE — Sieve out k^3 numbers
http://www.spoj.com/problems/PRIMES2/ (8) //VERY NICE — Some hell-shit optimizing
http://mirror.codeforces.com/contest/26/problem/A (2) //Easy — many ways to solve it
https://mirror.codeforces.com/contest/1180/problem/C (4) //[MODULO][QUEUE]
https://mirror.codeforces.com/gym/102001/problem/F (4) //[NICE][GREEDY]
https://mirror.codeforces.com/gym/101991/problem/D (4) //[NICE][NORMALIZE][PREFIX]
https://mirror.codeforces.com/gym/102021 L //[NICE][JUST DO IT]
https://mirror.codeforces.com/gym/102021 D //Try one and see
https://mirror.codeforces.com/gym/101972/problem/K (3) //[EASY][STRINGS]
http://mirror.codeforces.com/gym/101962/problem/K (3) //[NICE] //Complexity
http://mirror.codeforces.com/gym/101650 A //[VERY NICE][TREAP][PROBABILITY]
http://mirror.codeforces.com/gym/101650 K //[NICE] //Perhaps weak TC
https://abc084.contest.atcoder.jp/tasks/abc084_c (3) //Brute-Force
http://mirror.codeforces.com/contest/908/problem/B (2) //[EASY][NICE]
http://mirror.codeforces.com/contest/141/problem/B (3) //[NICE][IF-PARTY]
7921 — Anticlockwise Motion (4) //Simulate in sqrt
7691 — Falling Apples (3)
7977 — The Key to Cryptography (2)
http://mirror.codeforces.com/contest/129/problem/B (2) //Graph
http://mirror.codeforces.com/contest/903/problem/B (2) //[NICE]
http://mirror.codeforces.com/contest/120/problem/C (1)
http://mirror.codeforces.com/contest/118/problem/A (1)
8012 — Voting Fraud (1)
http://mirror.codeforces.com/contest/897/problem/A (1) //BF — do as they say
7985 — Bumper-to-Bumper Traffic (4) //FINE — We have whole time-lapse
7988 Flow Shop (3) //Do as they say. Trivial but not bad.
7703 — Reading Digits (2) //Simple simulate what they ask for
http://mirror.codeforces.com/contest/893/problem/A (1) //Easy but nice
http://mirror.codeforces.com/contest/102/problem/B (2) //Do as they write — log-convergence
http://mirror.codeforces.com/contest/92/problem/A (1) //Way too easy
http://mirror.codeforces.com/contest/88/problem/C (3) //[NUMBER THEORY]
http://mirror.codeforces.com/contest/84/problem/D (4) //Priority queue by min*size
http://mirror.codeforces.com/contest/79/problem/A (1) //Simulate rules
http://mirror.codeforces.com/contest/879/problem/A (1) //Iterate day-by-day
http://mirror.codeforces.com/contest/879/problem/B (3) //Either at most N^2 or the biggest element [NICE]
http://mirror.codeforces.com/contest/879/problem/D (4) //[NICE][Array elimination]
http://mirror.codeforces.com/contest/46/problem/A (2) //[EASY][MODULO]
http://mirror.codeforces.com/contest/46/problem/B (3) //[EASY][SEARCH-EACH-QUERY]
http://mirror.codeforces.com/contest/55/problem/A (2) //Simple (long) simulation
http://mirror.codeforces.com/contest/60/problem/A (1) //Moving LR bounds
12187 UVA (2)
http://mirror.codeforces.com/contest/724/problem/C 5
http://mirror.codeforces.com/contest/746/problem/C 3
11093 UVA (2)
http://mirror.codeforces.com/contest/768/problem/C (4)
http://www.spoj.com/problems/WRONG/ (5) //VERY NICE — precalculate from back, then go from front
http://mirror.codeforces.com/contest/864/problem/C (4) //Not nice — just iffs
http://www.spoj.com/problems/WAGE/ (3) //Simple Game Of Life Modification
http://mirror.codeforces.com/contest/6/problem/C (2) //Simple simulate from both sides
http://mirror.codeforces.com/contest/9/problem/B (2) //Simulate what is given (+ doubles)
http://mirror.codeforces.com/contest/11/problem/B (3) //sqrt(X) [diff must be even]
http://mirror.codeforces.com/contest/30/problem/A (2) //Simply simulate process [-1000→ 1000]
http://www.spoj.com/problems/ADATOMAT/
http://www.spoj.com/problems/ADAUSORT/
http://www.spoj.com/problems/ADACUT/
http://www.spoj.com/problems/ADAHLIA/
https://mirror.codeforces.com/contest/1174/problem/B (3) //[OBSERVATION] Nice yet simple
https://mirror.codeforces.com/contest/1174/problem/A (2) //[EASY]
https://mirror.codeforces.com/contest/1203/problem/E (4) //[GREEDY][SIMPLE]
https://mirror.codeforces.com/contest/1203/problem/B (3) //[GREEDY][NICE]
https://mirror.codeforces.com/contest/1185/problem/D (4) //[BF][IMPLE][MATH]
https://mirror.codeforces.com/contest/1185/problem/C1 (3) //[GREEDY]
https://mirror.codeforces.com/contest/1197/problem/C (4) //[NICE][EASY][OBSERVATION]
https://mirror.codeforces.com/contest/1197/problem/A (3) //[SIMPLE][GREEDY][MATH]
https://mirror.codeforces.com/contest/1189/problem/B (3) //[EASY][OBSERVATION]
https://www.spoj.com/problems/SWAPDIFF1/ (4) //[CLASSICAL][INVERSIONS]
https://www.spoj.com/problems/SHINCARD/ (4) //[NICE]
https://www.spoj.com/problems/POTATOPL/ (4) //[NICE][GREEDY]
https://mirror.codeforces.com/gym/101991/problem/I (3)
http://mirror.codeforces.com/gym/101962/problem/M (4)
http://mirror.codeforces.com/gym/101726/problem/E (3) //[STRUCTURES][IMPLEMENTATION]
13282 Cakey McCakeFace (3) //Brute Force
8260 Installing Apps (4) //[NICE] //Sorting + some DP
http://mirror.codeforces.com/contest/922/problem/D (3) //[NICE][GREEDY][EASY]
http://mirror.codeforces.com/contest/920/problem/C (3) //[EASY] Sortable by parts
http://mirror.codeforces.com/contest/913/problem/D (4) //[NICE][BS][2P][FW]
http://mirror.codeforces.com/contest/149/problem/A (2) //Sorting|Greedy
http://www.spoj.com/problems/SEUG/ (2) //Bad statement
http://mirror.codeforces.com/contest/141/problem/A (2) //Or frequency
http://mirror.codeforces.com/contest/137/problem/E (4) //[NICE][PREFIX SUM MATCHING]
http://mirror.codeforces.com/contest/137/problem/C (4) //[NICE][FENWICK WORKS TOO]
http://mirror.codeforces.com/contest/136/problem/C (3) //Last to 1(2) |OR| first to INF
7601 — Football (3) //Greedy
7673 — What a Simple Research (2) //[EASY][IMPLE]
http://mirror.codeforces.com/contest/108/problem/B (2) //Easy & Adjacent
8025 — Stacking Cups (2) //Sorting+input
http://mirror.codeforces.com/contest/892/problem/A (2) //[EASY][SUM]
https://www.urionlinejudge.com.br/judge/en/problems/view/2290 (3) //Sort+check [fast]
http://mirror.codeforces.com/contest/81/problem/C (3) //MATH[Lesser=greater][comparator]
http://mirror.codeforces.com/contest/53/problem/D (3) //Bubble sort
http://mirror.codeforces.com/contest/58/problem/D (4) //[BUCKET][GREEDY][STRING]
UVA 10810 //INV
UVA 11858 //INV
http://mirror.codeforces.com/problemset/problem/645/B //INV
UVA 10327 //INV
http://www.spoj.com/problems/BUBBLESORT/ //INV
UVA 11495 //INV [GAME]
http://www.spoj.com/problems/CODESPTB/ //INV
UVA 13212 //INV
http://mirror.codeforces.com/problemset/problem/749/E //INV
12189 UVA (3)
12196 UVA (4)
http://mirror.codeforces.com/contest/731/problem/D 7
11925 UVA (4)
11979 UVA (3)
http://mirror.codeforces.com/contest/747/problem/D (4)
11890 UVA (4)
http://www.spoj.com/problems/KAOS/ (4) //INV — GOOD problem!!!!
http://www.spoj.com/problems/KSMALL/ (5) //fast sort /or/ quick-select
http://www.spoj.com/problems/RKS/ (3) //use map
http://www.spoj.com/problems/SPCJ/ (4) //reverse + go from back
http://mirror.codeforces.com/contest/785/problem/B (2) //last-first + vice versa
http://mirror.codeforces.com/contest/798/problem/D (4) //Take 1st then take best B of every pair (sort by A)
http://mirror.codeforces.com/contest/810/problem/B (2)
http://mirror.codeforces.com/contest/810/problem/C (3) //+Math
http://mirror.codeforces.com/contest/814/problem/A (1) //Pro prváky — but nice observation
http://mirror.codeforces.com/contest/817/problem/B (3) //Frequency of TOP 3
10769 UVA (3) //Sadly N^4 passes
13208 UVA (4) //Sort + Prefix Sum
13212 UVA (3) //Number of inversions
http://mirror.codeforces.com/contest/831/problem/C (3) //NICE ~ Check all "add" against first
http://mirror.codeforces.com/contest/831/problem/D (4) //Can be solved with BS+Max-Match
http://mirror.codeforces.com/contest/841/problem/C (3) //NICE — match greatest to lowest
http://mirror.codeforces.com/contest/845/problem/C (2) //EASY — pro prvaky
http://www.spoj.com/problems/HSHW/ (4) //Test every big/low pair + big/big low/low on +/-
http://www.spoj.com/problems/CODESPTB/ (3) //Count inversions [BASIC]
http://mirror.codeforces.com/contest/863/problem/B (2) //Sort and omit 2
http://www.spoj.com/problems/AMR10G/ (2) //Easy yet NICE
http://mirror.codeforces.com/contest/12/problem/C (2) //Very simple
http://mirror.codeforces.com/contest/16/problem/B (1) //[EASY]
http://mirror.codeforces.com/contest/22/problem/D (3) //Sort by begin + sweep
http://mirror.codeforces.com/contest/23/problem/C (3) //Take them by pairs + add last
http://mirror.codeforces.com/contest/24/problem/B (3) //Simple follow the rules
http://mirror.codeforces.com/contest/27/problem/B (3) //Compare number of victories
http://mirror.codeforces.com/contest/27/problem/C (4) //[NICE] Find next bigger/lesser (sort)
https://www.urionlinejudge.com.br/judge/en/problems/view/2683 (3) //[BASIC][MAXIMUM]
http://mirror.codeforces.com/contest/908/problem/F (5) //[VERY NICE] //Not exactly MST but similar[GREEDY]
http://mirror.codeforces.com/contest/125/problem/E (5) //[BS]
http://mirror.codeforces.com/contest/76/problem/A (4) //[VERY NICE] Sort by A and KEEP spanning + one edge
LA 6622 — Absurdistan Roads (4) //Plus one edge
UVA 12176
UVA 10600
UVA 10724
https://www.hackerrank.com/contests/june-world-codesprint/challenges/johnland
UVA 11710
Gym 101252C [2014-2015 CT S02E05: Codeforces Trainings Season 2 Episode 5 — 2009-2010 ACM-ICPC]
Gym 101047I [2015 USP Try-outs][HARD]
UVA 11183 [Directed]
LightOJ 1101
https://www.codechef.com/problems/CHEFELEC
UVA 10307
http://mirror.codeforces.com/problemset/problem/598/D
http://mirror.codeforces.com/problemset/problem/32/C
http://mirror.codeforces.com/problemset/problem/744/A
https://devskill.com/CodingProblems/ViewProblem/344
908 — Re-connecting Computer Sites [UVA]
1208 — Oreon [UVA]
1235 — Anti Brute Force Lock [UVA]
10034 — Freckles [UVA]
11228 — Transportation system [UVA]
11631 — Dark roads [UVA]
11733 — Airports [UVA]
11747 — Heavy Cycle Edges [UVA]
BLINNET SPOJ (3)
11183 UVA (4) //Directed [need to know algo!]
http://www.spoj.com/problems/ULM09/ (3) //Sum-Kruskal
http://www.spoj.com/problems/IITKWPCG/ (4) //VERY NICE [log instead of price]
http://mirror.codeforces.com/contest/17/problem/B (3) //Spanning tree [no dsu]
LightOJ 1074
UVA 1171
UVA 11478
UVA 12768
11478 UVA (5)
https://mirror.codeforces.com/contest/1199/problem/D (4) //[NICE][SIMPLE IMPLE]
https://www.spoj.com/problems/ZING01/ (5) //[VERY NICE][STRING][SEGMENT]
http://mirror.codeforces.com/gym/101889 D //[NICE][STL]
http://mirror.codeforces.com/contest/916/problem/D (6) //[NICE][BS][BINARY-LIFTING]
12003 UVA 7
11990 UVA (5)
http://www.spoj.com/problems/GIVEAWAY/ (7) //SQRT + BS > [or Seg+Trie]
http://mirror.codeforces.com/contest/786/problem/C (5) //Nsqrn (bg) + sqrSegs (end)
http://mirror.codeforces.com/contest/840/problem/D (5) //NICE — Either frequent OR brute-force
http://mirror.codeforces.com/contest/13/problem/E //VERY NICE [SQRT-BLOCK UPDATE/JUMP]
http://mirror.codeforces.com/contest/85/problem/D (4) //NICE [ST shall work too]
http://www.spoj.com/problems/ADABASET/ [IO-testing][ARRAY]
http://www.spoj.com/problems/ADALIST/ [ROPE]
http://www.spoj.com/problems/ADAFIELD/ [SET]
http://www.spoj.com/problems/ADAQUEUE/
http://www.spoj.com/problems/ADAFRIEN/
https://www.spoj.com/problems/REDARR2/ (4) //[NICE][PQ]
https://www.spoj.com/problems/MINSTOCK/ (3) //[EASY][MAP]
http://mirror.codeforces.com/gym/101864 F //[SET]
http://mirror.codeforces.com/contest/920/problem/B (3) //[NICE][QUEUE][SIMPLE]
http://mirror.codeforces.com/contest/911/problem/E (4) //[NICE][STACK][SET]
http://mirror.codeforces.com/contest/909/problem/D (4) //[VERY NICE][SIMULATION][GROUP]
http://mirror.codeforces.com/contest/899/problem/E (4) //[VERY NICE][SET]
https://arc087.contest.atcoder.jp/tasks/arc087_a (2) //Map
http://mirror.codeforces.com/contest/903/problem/C (2) //Map
http://mirror.codeforces.com/contest/900/problem/C (3) //[NICE][SET]
http://mirror.codeforces.com/contest/112/problem/A (1) //tolower [trivial]
3396 — Alphabetics (2) //Getline, letters identification
http://mirror.codeforces.com/contest/81/problem/A (2) //Stack OR string
http://mirror.codeforces.com/contest/78/problem/A (1) //fgets + imple
http://mirror.codeforces.com/contest/69/problem/E (3) //NICE [2POINTERS][SET][MAP]
http://www.spoj.com/problems/RMID/ //Dynamic Median
http://www.spoj.com/problems/RMID2/ //Dynamic Median
http://mirror.codeforces.com/problemset/problem/713/C //Dynamic Median
http://www.spoj.com/problems/EC_ESTA/ //Dynamic median
http://mirror.codeforces.com/contest/799/problem/B (2) //EASY — MAP
http://mirror.codeforces.com/contest/808/problem/D (3) //MAP
10887 (2) //string + map
10730 (3) //Easy with hash-map
http://mirror.codeforces.com/contest/821/problem/C (3) //STACK (vector) Nice+Easy
http://www.spoj.com/problems/SOLVEIT/ (3) //Set + lower_bound
http://www.spoj.com/problems/IITKWPCA/ (2) //Set + getline
http://mirror.codeforces.com/contest/849/problem/D (5) //Queue
http://www.spoj.com/problems/CRAN02/ (4) //Map (+Math)
http://www.spoj.com/problems/MAX_NUM/ (4) //Queue (possibly multiple ways)
http://www.spoj.com/problems/SID/ (5) //Sort + Vector (or similar) [strict TLE]
http://www.spoj.com/problems/RPLD/ (2) //Map of sets
http://mirror.codeforces.com/contest/861/problem/D (4) //unordered map of sets
http://www.spoj.com/problems/FACEFRND/ (2) //Set or Bitset
http://www.spoj.com/problems/HACKRNDM/ (3) //Easy — map
http://mirror.codeforces.com/contest/847/problem/K (4) //NICE Map+Queue
http://mirror.codeforces.com/contest/855/problem/A (1) //set
http://mirror.codeforces.com/contest/4/problem/C (2) //map+string
http://mirror.codeforces.com/contest/5/problem/E (6) //iffs + RMQ+BS+SET [or other sol]
http://mirror.codeforces.com/contest/44/problem/A (1) //Set + pair
http://mirror.codeforces.com/contest/45/problem/C (4) //NICE — Handling with sets
http://mirror.codeforces.com/contest/918/problem/B (2) //[MAP] //TLDR
https://mirror.codeforces.com/contest/1189/problem/A (2) //[OBSERVATION]
https://mirror.codeforces.com/contest/1194/problem/C (3) //[EASY][FREQUENCY][2POINTERS]
https://www.spoj.com/problems/MAGSUB1/ (3) //[EASY][SYMPATHIC][COMBINATORICS]
https://www.urionlinejudge.com.br/judge/en/problems/view/2866 (1) //Reverse
https://mirror.codeforces.com/gym/101972/problem/H (3) //[NICE][PREPROCESS]
http://mirror.codeforces.com/contest/909/problem/A (1) //Lexicographical comparision [EASY]
7948 Periodic Strings (2) //Brute-force
7892 — Game of Matchings (6) //No idea — heuristic works — but seems to be nice
8017 — Mancunian and Sonu Generate Strings (5) //[NICE][DP]//+Something: Trie/SA/SET...?
http://mirror.codeforces.com/contest/890/problem/D (4) //[NICE][SET][SORTING][26][BRUTE-FORCE]
http://mirror.codeforces.com/contest/43/problem/B (2) //Frequency
http://mirror.codeforces.com/contest/50/problem/B (2) //Frequency + Power
http://www.spoj.com/problems/MINMOVE/ (3) //Minimal lexicographical rotation
http://www.spoj.com/problems/BWHEELER/ //Burrows Wheeler
http://www.spoj.com/problems/EDIST/ //Edit Distance
3189 LA //Edit Distance
https://www.hackerrank.com/contests/morgan-stanley-2015/challenges/minimum-transformation-cost/problem //Edit Distance
http://mirror.codeforces.com/gym/101492/problem/L //Laevenstein Distance
UVA 13068 //Lexicographically lowest rotation
2755 [LA]//Lexicographically lowest rotation
LightOJ 1073 //Lexicographically Shortest Superstring
http://mirror.codeforces.com/contest/762/problem/C 5
http://www.spoj.com/problems/LCS0/ 10 //LCS
http://www.spoj.com/problems/IITWPC4H/ 2 //Frequence array
13186 UVA (6) //Bitset + Trie ~ NICE [6-7 mby?]
http://mirror.codeforces.com/contest/798/problem/B (2) //Brute-force .. pro prváky
10745 UVA (4) //Frequency (N^2 possible if efficient!!)
http://mirror.codeforces.com/contest/822/problem/B (2) //Easy pro prvaky (slightly imple.)
http://mirror.codeforces.com/contest/828/problem/C (4) //+Sorting (process only necessary!)
http://mirror.codeforces.com/contest/832/problem/B (3) //Naive compare back+front [+freq]
http://www.spoj.com/problems/STC04/ (5) //Next + pairs O(N*26) [frist look O(26^2*N)]
http://www.spoj.com/problems/IITKWPCJ/ (4) //GCD or HASHING
http://www.spoj.com/problems/SUBSN/ (4) //Next (NICE — bad input):
http://www.spoj.com/problems/BOGGLE/ (2) //EASY [MAP][STREAM]
http://www.spoj.com/problems/MAIN8_E/ (4) //VERY NICE — Next function
http://www.spoj.com/problems/STRMATCH/ (3) //Nice matching, yet low constraints on "N"
http://www.spoj.com/problems/FINDSR/ (3) //Clever bruteforce works here (NlogN)
http://mirror.codeforces.com/contest/39/problem/J (2) //Simple iteration over string
http://mirror.codeforces.com/contest/876/problem/E (4) //Compare from back + make fail-pairs
http://www.spoj.com/problems/ADAPHOTO/ [or hashing after turboanalisis]
http://www.spoj.com/problems/ADASTRNG/
https://mirror.codeforces.com/contest/1202/problem/E (5) //[NICE][OBSERVATION][RMQ]
https://mirror.codeforces.com/gym/101991/problem/E (6) //[VERY NICE][RMQ]Prolly an easier alternative
https://toph.co/p/distinctness (6) //[VERY NICE][SET][LCP][RMQ]
http://mirror.codeforces.com/gym/101889 M //[VERY NICE][OBSERVATION]
http://mirror.codeforces.com/gym/101840 B //[NICE][ST][BIT][LCP]
http://mirror.codeforces.com/contest/129/problem/D (4) //[NICE]//Suffix Automaton / Brute Force works too
http://mirror.codeforces.com/contest/123/problem/D (5) //[NICE][RMQ][D&C]
8086 Substring Sorting (7) //[VERY NICE][RMQ][BS][PST]
7702 — Castle //6 [VERY NICE][RMQ][BS][FW]
7701 — Favorite music //8 [VERY NICE][RMQ][SEARCH][OPTI] //WRONG TIME-LIMIT==OPTI
https://www.urionlinejudge.com.br/judge/en/problems/view/1530 //7 [VERY NICE][RMQ][SET][OFFLINE]
https://www.urionlinejudge.com.br/judge/en/problems/view/2000 (5) //Basic disubstr counting
UVA 760 //LCS
UVA 1227 //LCS
http://www.spoj.com/problems/LCS/en/ //LCS
UVA 11512
7502 [LA]
Gym 100923D [2015 ACM National Contest Romania — Round 1]
UVA 1254
UVA 12191
UVA 12206
https://www.codechef.com/problems/INSQ16F
3943 LA
UVA 11107
UVA 12974
UVA 10526
Davos and Reading [INSOMNIA] //Awesome problem but can't find link [hard] — non of regular judges
UVA 12338
https://devskill.com/CodingProblems/ViewProblem/328
12191 UVA 5
SARRAY SPOJ 3
4513 LA 6
http://www.spoj.com/problems/LCS2/ 7 // must be linear (SA+LCP+MQ)
http://mirror.codeforces.com/contest/802/problem/I 7 //NICE! SA+LCP+(Segmentree/queue)
http://www.spoj.com/problems/LONGCS/ //5 LCS of multiple strings (NICE)
http://www.spoj.com/problems/SUBLEX/ //5 VERY NICE: Kth substring
http://mirror.codeforces.com/contest/873/problem/F //6 VERY NICE: SA+Histogram
http://mirror.codeforces.com/contest/30/problem/E //7 VERY NICE: [many other sols: Manach/KMP/HASH...]
6856 — Circle of digits //7 [VERY NICE]
LightOJ 1146
Gym 101482G [2014-2015 Northwestern European Regional Contest (NWERC 2014)]
Gym 101309D [2010-2011 ACM-ICPC Northeastern European Regional Contest (NEERC 10)]
UVA 13010 //+Dijkstra
2015-2016 CTU Open Contest: Chasing the Cheetah
12197 UVA (4)
http://www.spoj.com/problems/KOPC12A/ (4) //TS (sadly brute-force works too N^2)
https://mirror.codeforces.com/gym/102058/problem/A (5) //[NICE][2TIMES][PRIORITY]
UVA 11686
LightOJ 1034
UVA 10305
124 — Following Orders [UVA]
200 — Rare Order [UVA]
872 — Ordering [UVA]
11060 — Beverages [UVA]
http://mirror.codeforces.com/contest/765/problem/E 5
http://mirror.codeforces.com/contest/770/problem/C 4 //reduce + toposort
http://mirror.codeforces.com/contest/825/problem/E 4 //Toposort from biggest/backward
http://www.spoj.com/problems/CODESPTI/ (6) //VERY NICE — Hard/Weak children
http://mirror.codeforces.com/contest/47/problem/B (2) //[EASY][Toposort on 3 elements]
http://mirror.codeforces.com/contest/909/problem/E (4) //[NICE][BFS][RECURSION]
https://mirror.codeforces.com/contest/1181/problem/D (5) //[VERY NICE][SORTING][OFFLINE]
https://www.hackerrank.com/challenges/find-the-running-median/problem (4) //[NICE][HEAPS]
http://mirror.codeforces.com/gym/101992/problem/M (4) //[NICE][OFFLINE][SORTING]
http://mirror.codeforces.com/gym/100112 C //[VERY NICE]
http://mirror.codeforces.com/gym/101864 B //[NICE] Lesser than
http://mirror.codeforces.com/contest/899/problem/F (5) //[VERY NICE][DATA STRUCTURE] (FW or Treap)
http://mirror.codeforces.com/contest/879/problem/E (6) //[VERY NICE][Making somponents]
http://www.spoj.com/problems/ADAAPHID/ [or clever fenwick][or SQRT-tree]
http://www.spoj.com/problems/ADACROP/
http://mirror.codeforces.com/contest/762/problem/E 6
http://www.spoj.com/problems/COUNT1IT/ 5
http://www.spoj.com/problems/IITWPC4D/ 4 //From end — pick i-th + del i-th
http://www.spoj.com/problems/ALLIN1/ 4 //Typical treap operations
http://mirror.codeforces.com/contest/847/problem/D 5 //Prolly overkill — VERY NICE
http://mirror.codeforces.com/contest/863/problem/D 4 //Not desired solution
http://www.spoj.com/problems/KOILINE/ (4) //VERY NICE — Iterate from back — get+remove
http://www.spoj.com/problems/TWIST/ (5) //NICE: Reverse
http://www.spoj.com/problems/MEANARR/ (5) //VERY NICE! [POLICY][SHORT]
http://www.spoj.com/problems/ADATOMEL/
https://mirror.codeforces.com/contest/1189/problem/D1 (4) //[OBSERVATION]
http://mirror.codeforces.com/contest/913/problem/B (2) //Simple check
http://mirror.codeforces.com/contest/894/problem/D (5) //[NICE][MERGING][BINARY]
http://mirror.codeforces.com/contest/746/problem/G 5
http://mirror.codeforces.com/contest/750/problem/F 9
http://www.spoj.com/problems/RTREE/ 3 //longest path tree — query
13175 UVA (2) //something like preorder build
http://mirror.codeforces.com/contest/796/problem/C (3) //Just counting — inc by at most 2
http://mirror.codeforces.com/contest/797/problem/D (4) //VERY NICE — sort + D&C all
http://mirror.codeforces.com/contest/805/problem/E (4) //NICE — Treewidth coloring (greedy)
http://mirror.codeforces.com/contest/828/problem/D (3) //Star construction
http://www.spoj.com/problems/TREEDEGREE/ (3) //Degree from euler tree
http://www.spoj.com/problems/UCV2013J/ (3) //Find what is leaf in Binary Tree
http://www.spoj.com/problems/GCPC11J/ (3) //Finding ceter
http://mirror.codeforces.com/contest/34/problem/D (3) //Simple reconstruction + DFS
http://www.spoj.com/problems/ADASALES/
https://mirror.codeforces.com/contest/1187/problem/E (5) //[VERY NICE][DFS]
http://www.spoj.com/problems/PT07X/ (4) //Classical- VC on tree [NICE]
http://mirror.codeforces.com/contest/81/problem/E (6) //[NICE][PSEUDOFOREST REDUCTION]
http://mirror.codeforces.com/contest/61/problem/D (4) //dfs-only might works too
LA 6631 — Jingle Balls (4) //[NICE][SIMPLE]
https://www.codechef.com/problems/TRANDED //By sahil070197
13089 — Golden Coins (UVA)
http://mirror.codeforces.com/problemset/problem/855/C
http://mirror.codeforces.com/problemset/problem/718/D
https://www.codechef.com/problems/TWOCOINS
https://www.hackerrank.com/contests/101hack35/challenges/road-maintenance/problem
7649 — Performance Review (LA)
http://mirror.codeforces.com/problemset/problem/741/D
http://mirror.codeforces.com/problemset/problem/592/D
https://www.codechef.com/problems/TOMJERGA
http://mirror.codeforces.com/problemset/problem/814/D
1220 — Party at Hali-Bula (UVA)
https://www.hackerrank.com/contests/june-world-codesprint/challenges/r-tree-decoration/problem
12452 — Plants vs. Zombies HD SP (UVA)
http://mirror.codeforces.com/problemset/problem/735/E
https://www.codechef.com/problems/COLTREE
12466 — Ancestors (UVA)
6829 — Intrepid climber (LA)
https://www.hackerrank.com/contests/101hack35/challenges/jeanies-route
12257 — The Queue (UVA)
http://mirror.codeforces.com/problemset/problem/805/F
http://mirror.codeforces.com/problemset/problem/763/D
1218 — Perfect Service
3346 — Perfect Domination on Trees (same as above -_-)
12093 — Protecting Zonk
10859 — Placing Lampposts
http://mirror.codeforces.com/problemset/problem/23/E //NICE [but requires big int]
http://mirror.codeforces.com/problemset/problem/14/D (5) //NICE [sorting-one][2DFS]
http://www.spoj.com/problems/TWOPATHS/ (6) //VERY NICE Same as above ~ bigger constraints
http://mirror.codeforces.com/contest/868/problem/E (8) //VERY NICE — HARD — on tree
https://www.spoj.com/problems/XORX/ (4) //[NICE][BASIC][PREFIXXOR]
http://mirror.codeforces.com/contest/888/problem/G (5) //NICE[BIT-BY-BIT D&C]
http://mirror.codeforces.com/contest/842/problem/D //Proposed by usernameson
http://mirror.codeforces.com/problemset/problem/706/D
https://www.hackerrank.com/contests/w8/challenges/black-box-1
https://csacademy.com/contest/round-42/task/xor-submatrix/
http://mirror.codeforces.com/contest/714/problem/C 5
http://www.spoj.com/problems/SUBXOR/ (4)
http://mirror.codeforces.com/contest/817/problem/E (5) //Classical — remember sum! NICE!
http://mirror.codeforces.com/contest/37/problem/C (4) //NICE — Prefix dictionary [or math]
http://www.spoj.com/problems/ADAINDEX/
http://mirror.codeforces.com/gym/101628/problem/K (5) //[NICE][IMPLEMENTATION]
8015 — Alice and Bob play Contact (5) //[VERY NICE] 1stBob
2642 [LA]
UVA 10860
UVA 10295
UVA 13186 //+Bitset
UVA 1123
UVA 12506
UVA 11539
UVA 1142
UVA 12359
UVA 10282
11732 UVA (5)
11539 UVA (5)
11488 UVA (4)
http://www.spoj.com/problems/TRYCOMP/ (4)
10860 UVA (4) //DP + Trie [nice — slightly generic]
http://www.spoj.com/problems/DICT/ (4) //Sample trie — but slightly weak/wrong data-set
https://www.urionlinejudge.com.br/judge/en/problems/view/2810 (5) //[NICE][DOUBLE]
Gym 100818E [2015-2016 ACM-ICPC Southeastern European Regional Programming Contest (SEERC 2015)]
3725 [LA]
UVA 10496
Gym 101020H [2015 Syrian Private Universities Collegiate Programming Contest] N!
LightOJ 1057
UVA 11643 //[NICE][BFS]
3305 [LA] //On plane
10937 UVA (4) //find '!' / BFS / TSP — NICE!
10944 UVA (4)
10818 UVA (5) //Easy — but not-easy implementation: ++Dijkstra [LEX!]
http://www.spoj.com/problems/A_W_S_N/ (4) //BFS + TSP (path) — NICE
http://www.spoj.com/problems/ADAFENCE/ [Multiple Pointers]
http://www.spoj.com/problems/ADAPLANT/
https://mirror.codeforces.com/contest/1175/problem/C (4) //[NICE][GREEDY]
https://mirror.codeforces.com/contest/1203/problem/D1 (4) //[VERY NICE][STRINGS][PREPROCESS]
https://mirror.codeforces.com/contest/1203/problem/D2 (5) //[VERY NICE][STRINGS][PREPROCESS]
https://mirror.codeforces.com/contest/1186/problem/C (4) //[VERY NICE][BITS][OBSERVATION]
https://www.spoj.com/problems/MOZHCAN/ (5) //[VERY NICE]
http://mirror.codeforces.com/gym/101864 L //Static Size [SORTING]
Dev Skills-499: Closest Pair Point (4) //[NICE][GEOMETRY][STRUCTURES]
http://mirror.codeforces.com/contest/919/problem/C (3) //Similar — simple sweep [EASY]
http://mirror.codeforces.com/contest/144/problem/C (3) //[NICE][FREQUENCY][STRINGS]
http://mirror.codeforces.com/contest/895/problem/B (3) //[OR BS]
http://mirror.codeforces.com/contest/84/problem/B (2) //EASY //ll
http://mirror.codeforces.com/contest/79/problem/C (4) //NICE — [STRINGS][SET][COMPARE]
http://mirror.codeforces.com/contest/746/problem/F 6
11436 UVA (5)
http://mirror.codeforces.com/contest/760/problem/D 4
11386 UVA (4)
http://www.spoj.com/problems/WOWSUBSTR2/ 3
http://www.spoj.com/problems/ARRAYSUB/ 4
http://www.spoj.com/problems/CODFURY/ 3 //easy — ukazkove
http://mirror.codeforces.com/contest/769/problem/B 3 //sort + TP
http://mirror.codeforces.com/contest/814/problem/C 4 //NICE — maybe some DP +/-
http://www.spoj.com/problems/CRAN04/ 4 //NICE — (more or less) 3 pointers
http://www.spoj.com/problems/OPCPIZZA/ 3 //NICE [EASY] [AGAINS EACH OTHER]
http://www.spoj.com/problems/ALIEN/ (3) //Classical
http://www.spoj.com/problems/HOTELS/ (3) //Classical & Easy
http://www.spoj.com/problems/KOIREP/ (4) //VERY NICE — N buckedt find mid diff
http://mirror.codeforces.com/contest/6/problem/E (4) //NICE — Multiset
http://mirror.codeforces.com/contest/873/problem/C (3) //NICE — M times 2P tenchique
https://www.urionlinejudge.com.br/judge/en/problems/view/1348 (4) //[CLASSICAL][NICE][SCC]
11930 UVA (4)
Finally if you would like to add some problem to the list — even though I would be glad, please do so only in case of:
It is very interesting
There is nothing, or low number of problems in the topic
You add it in "bigger amount" at once
Thank you.
Offcourse if you have any remarks, questionns or requests, don't hesitate to ask.
PS: I'm sorry but there might be some duplicities. In that case, either report it or ignore it (unless they are in different topics, then it have reason :) )
Good Luck & Have Nice Day
Thank You :)
It seems that you don't like Möbius inversion much.
Hello, Yes,
I'm not mathematician and it seems slightly like magic to me :'( I find it hard somehow :/
Good day to You too, I'm sorry to ask such a question, but I really couldn't really find where I can submit problem called "8015 — Alice and Bob play Contact" in a division trie_string, because when I go to UVA and insert a value 8015 in a problem id in a Quick Submit, I get a message: "The selected problem ID does not exist.", what is its actual id by which I can submit the problem?
good day to you,
seems to be on Live Archive
Well, can You please help me out with one more issue, when I try to register to icpcarchive.ecs.baylor.edu, it gives me this error, how to fix it?
Sorry — no idea what the error means :'(
Hello there! I know it has been a very long time but I was trying to solve this problem PAIRDIV, and I couldn't solve it using mobius inversion. I managed to solve it in another way though, but I would like to know how to solve it with mobius inversion. Can you help me, please?
Are the numbers in the parenthesis your judgement of how difficult each problem is?
Good day to you,
yes, exactly as you say. But as it is stated — it is my opinion so it might be "a little bit" off :)
I find it funny that there is a topic "oeis". xD
Good day to you,
well right :D .. it is mostly math.
It is might be used slightly in "different" manner then normal math problems. I.e. you can brute-force small test-cases only and then "google the rest" .. So math but basically different approach ^_^
Can you please tell what are the problems from LA are?? i mean what is LA?? i have never heard of it.
Good day to you,
sure: LA stands for Live Archive — it is a judge which stores most of the problems from Regional Contests + World Finals
Ok... never came across the acronym before :).Thnx for the prompt reply.
what is "big"?
Good day to you,
This topic stands for Big Integer — so problems with numbers which doesn't fit in 264 :)
Have Nice Day ^-^
I think you mean to say Integer.
Yes, thank you — fixed this :)
I've got a nice problem for tree-dp
Torque and edges
are all the questions tough or are some questions easy, how does a pupil like me approach those questions??? I simply want to ask that how do i use this resource for optimum benefit!!!
Good day to you,
imho there shall be easy questions too. Some of them are marked by a number (by which I've tried to estimate the difficulty). So you might try (firstly) problems marked with lower numbers (lets say lesser/equal 3 or 4)
Wish you a nice day,
~/Morass
thank you for such a quick reply. is the estimate out of 10.
Yes it is out of 10 (even thought — I think I've never used such big number :P) [but again.. it is just estimation, so might not be absolutely correct :) ]
can you give an estimate that what will be my rating like if I solve questions till level a)5 b)6 c)7 d)8(will take a long time to reach here.)
Unfortunatelly it is not much possible imho :'(
Firstly, even person with lover rating can solve hard problem. It will just take him more time to come-up with solution and/or to code the solution.
Secondly some problems fit to some people more — so it varies.
Another thing is that many problems here are algorithmic. So sometime the hardest part might be algorithm itself. It indeed might be hard to code — and even more difficult to come with. On the other hand, it is not that hard to find such algorithm somewhere on google, learn it, code it.. and then it colsts "nothing" when you use it for the second time (even thought It costed many hours for the first time).
So in my opinion, I can't say it... Anyway if you would be able to do that fast (so it would easily fit into codeforces contest) the rating might possibly probabli be somewhere between purpble to red (the range you told)
Also note, that codeforces stile problems might be different from "ACM"-stlye problems... and also from some direct-method SPOJ problems.
So well, sorry this didn't help you much, but that is my opinion :)
No No, infact I WANTED an answer to my silly question but you gave me the answer I NEEDED to progress further, thank you so much!!
Sir, what do you think about the book — competitive programming 3 -by steven halim and felix halim? If I solve all the problems mentioned in that book will I improve? If yes, then how much?
Good day to you,
Well firstly, I've not read the book so not sure if my answer will be "valid". Anyway I know some people who did so (and I've also heard a little bit about it and so on):
The book introduces most of the algorithms which are considered "basic" so imho it is "almost necessary" to know these algorithms as "ground" for almost any (at least a little bit) advanced skill-level. I heard it is a great book (the algorithms are well described there) so it is worth giving it a try (well you shall learn the algorithm somewhere — so why not from here?). Anyway what I also think is, that it won't ensure you any of the skill-levels: There are many more thinks, which "shuffled" together makes you good at CP and the knowledge of algorithms is "only" (but it is imho important) one of the "carrier pillars".
Again, I haven't read it and this is just my option :)
Wish you a nice day ^_^
This one is nice for Z function . https://www.codechef.com/problems/CHSTR
Good day to you
Thank you very much for suggestion, anyway sadly I'm not able to edit my blog anymore to add it :'(
Seems I'm getting "504 Gateway Time-out" every time I try so and I'm unable to resolve this problem .. sorry :'(
Its ok. Thank you for the wonderful list :)
840D - Destiny is a nice example of a tricky wavelet tree.
842D - Vitya and Strange Lesson is another trie_bit problem it might be a good addition since the trie_bit list is pretty small.
Good day to you sahil070197 GreenGrape usernameson,
Thank you for your contriution. Sadly I can't update the blog anymore (due to "504 Gateway Time-out") :'(
If I would miraculously evade it one day, I'll add those problems,
Good Luck & Have Nice Day!
It would be the greatest help i have ever had on CODEFORCES if you added articles for each type of problems. Because after learning the type of algorithm, the problem list you wrote is the best to deepen it. Anyway thanks a lot BRO!!!.
by the way your post is already is the best profit . . .:)
That's what we're trying to do https://e-maxx-eng.appspot.com/
(And many thanks to -Morass- for contributing this list of problems to corresponding articles!)
Hello! Why do you have two "Zfunction" tags? Do they serve different purpose?
Good day to you,
nope, seems to be mistake, thank you :)
Add this to geometry: https://icpc.kattis.com/problems/airport Really nice problem :)
Aho-Corasick: http://mirror.codeforces.com/problemset/problem/346/B
Auto comment: topic has been updated by -Morass- (previous revision, new revision, compare).
Congrats, I see you managed to get around 504-Gateway Time-out.
Thanx ... I was trying for more than week and now it magicaly worked .. I was really surprised :)
Thank you very much, very interesting:))
Nice list! Thanks
I also use the Categories section on ahmed_aly's A2 online judge.
Auto comment: topic has been updated by -Morass- (previous revision, new revision, compare).
Hello sir, I am doing CP for over a year now(though not on CF) and have learnt basic algorithms(those taught in 6.006 class MIT). What according to you should I do to improve my skills?
EDIT:I forgot to mention that nowadays I am giving contests and reading blogs of people on CF and topcoder but I cannot get 100% of what author is trying to say(in editorial or blog):(
Is there anything I can do or should not do at this point of time?
Thank you.
Good day to you,
Firstly, this is HARD KIND of question, since it is not directly on CP but slightly on "psychology"/"learning" which might be different for different people (so question is whether programmers are the right people to answer this question). Also, as you can see, my progress is not that good so maybe it would be better to ask some red-coder (or nutela).
Here is the text I typically use for such kind of question so hope you'll find something in it:
In first place, one need obtain knowledge in basic algorithms: There are many algorithms which are not hard, yet it is hard to do even medium (sometime easy) problems without them. Starting from dfs/bfs/sieve/graph-algos/sorting/....(many many other). So find some way to learn them. Usually, find some good blod (codeforces/geeksforgeeks/some school's lectures/so on..).
While doing the above, one has to catch some coding/debugging concepts. Afterward it is imho good to do many easy (at most medium) problems to improve coding skills. Even though many people undeestimate this, it is very important to get to phase where you can code what you know (well, it might sound stupid, but many times one know a solution one hour before end of contest, yet he ends coding 10 minutes before end when he starts his 20 minute debugging phase [and both could be significantly reduced])
As one improves (hopefully), he must start doing harder and harder problems and soon with the harder problems, he must lear also advanced algorithms: Suffix Array/HLD/Segment Trees/...(and many many others) which are usually not "that" necessary for easier problems.
Also during all phases, it is good (even thougt one spends a lot of time by coding) spend some time by reading:
a) New algorithms helpful things b) Editorials for what one doesn't know (firstly THINK about the problems and if nothing come, search for solution. Sometime one just find he's "stupid" but many times one discovers "new amazing" techniques)
Also sometimes it is interesting to peek to solution of others... even (or maybe BEST) after you solve the problem. Sometimes there is much better solution then you came with, sometimes there is something awesome (like algorithmic/or/language trick) which might simplify your futher coding.
Also sometimes it is good to "measure twice, cut once"... thinking for a while even if you know the solution. Sometime you find improvement, or reduce it by redundant part..
anyway... solve solve solve ~ that it what I usually do :)
Good Luck & Wish you a Nice Day!
Thank you for guidance!
Just the thing I want in my semester break vacation!
Thanks A Lot!
Recently I was learn Link Cut Tree. Have any list of problems set of link cut tree? Help Me to find out.
Good day to you,
only a few — unroll "lct".
Thank You! :)
is problem set arranged in order of ascending difficulty?
Good day to you,
nope it is not. Some problems mighthave number next_to them, which is estimated difficulty, but it is just "a very wild guess" :).
Wish you a nice day!
Strongly Connected Components(SCC) http://mirror.codeforces.com/problemset/problem/427/C
Good day to you!
Thank you very much. I've (hopefully) updated the topic!
Wish you a nice day!
In your MO part there is a problem(https://toph.ws/p/distinct-dishting). The link has changed. It's now https://toph.co/p/distinct-dishting. If you have listed any other problem from that site I think the link should be updated.
Did you simply miss HLD or it's there but I can't find it?
Good day to you,
HLD is there as part of "LCA"
Can someone explain what is the solution for this problem? http://www.spoj.com/problems/AMR10J/
I am thinking a dp on tree solution, something like O(N*K^2) but that would be too slow. No clue how the problem tag you mentioned, of DAG, would help. Isn't the graph in the form of a forest, with each tree having only one cycle?
Hints would probably be more appreciated though, seems like an interesting problem. :)
EDIT:
Help no longer needed! Managed to solve it in just O(N) and N is only <= 100. Pretty neat. In case anyone is interested, here is the code: https://pastebin.com/GrvCjSwt
As I was browsing here this problem caught my eye. I have made not much progress in a week or so other than determining the shape of each component (multiple trees hanging from a cycle).
Could you please explain your dp idea? For example, what does DP[i][j] represent?
Is there a CHT list?
Good day to you,
sorry but not :'( Maybe there is something in Number Theory but I wouln't bet on many problems
Wish you a nice day!
Some more easy problems on Josephus : http://www.spoj.com/problems/WTK/ (Easy) http://www.spoj.com/problems/DANGER/ (Easy) http://www.spoj.com/problems/POCRI/ (Medium) http://www.spoj.com/problems/NG0FRCTN/ (Medium)
Good day to you,
thank you very much. I wanted to reply after update yet sadly I'm getting 504 Gateway Time-out when trying to update for more two week already so sorry, and I hope it will get better once :'(
Wish you a nice day!
It's my pleasure to get a reply from you! Great efforts in Compilation, really useful.
Bridge Problem : http://mirror.codeforces.com/contest/1000/problem/E
the question ada and power mentioned in friedvald algorithm section is giving wa for test file 15. please give some insights
I have an Idea for you if you can do it.
Example :
Some problems links here
Some problems links here
What does "L-mex" stand for in the segment tree section?
Good day to you,
not much sure now — yet imho firstly there is some check with "L" parameter... and then probably getting "MEX" (minimal unused value).
dunno — sorry :P
Wish you a nice day ^_^
hey, Can somebody help me with this problem Ada and Zoo
thanks :)
Good day to you,
I would recommend you to take peek onto Steiner's Tree -> That shall be a great start ^_^
Good Luck
Thank you!
You should erase most categories from that list, because they are useless. Problemsetters no longer know what most of those categories are.
RMQ? KMP? LCA? What's all that? Might be some names for prehistoric problem solving techniques. All you need today is math, some thinking and three lines of code.
I wish there were tutorials and solutions gathered for these problems :D
What do you mean by hard/weak children? (in category 'topo', problem : spoj — 'CODESPTI')
Good day to you,
well it was just kind of hint that in my approach you should distinguish nodes by their "shape" (which recursively applies)
This one link could be interesting for persistent segment tree, for me it was...
Please anyone give the link for problem 4956 [LA] . category : friedvaldAlgorithm
Good day to you,
the link shall be here
I wrote a script to save all these questions along with their categories in a CSV file using python. Here is Pastebin link if you would like to use it.
I have saved your code on one of the repls, so you can just run and get the file directly (Link).
Thanks a lot! I shall add this link to my blog post if you have no problem.
I think 576C is the most classical problem for MO's algorithm. So that's good to add it.
-Morass- Can You say the total numbers (digit) :p of the problem listed here :D :D
sorry my bad
Thank you so much! I will definitely use this to structure my training. I appreciate all of the div 1 codeforcers helping out the rest of us!
Hey -Morass- I've been trying to solve SPOJ — JUSTAPAL from the palindrome category using hashing + binsearch and then using nlogn SA + LCP + RMQ to get first and second mismatches and do some swaps. However I'm still getting TLE. Is there something to take into account for getting a faster solution. Can you please share a hint or your code about this one? Thanks! :)
Hmm okkey not sure whether BS + Hashing wouldn't time-out actually..
Anyways SA+LCP+RMQ seems to be right solution. Guess with this (you can check your local build-time, whether it is not too slow already --> it is NlogN so it shall be slowest part I guess, but shall not time-out: So try it/check it out), it shall be linear: For each possible "middle" check how far you can have palindrome -> then "repair" the next part and check whether the palindrome can continue .. and possibly whether it was "repaired" by swaping the next broken part and possibly check how far you get next....
So in the end (omitting build part): There shall be (+/-) 2N such processes, with at most 3 RMQ questions and a few peeks to array: So this part shall be linear and hopefully shall not time-out.
So if this is your approach, then it shall be fast enough (if there is no mistake :O )
-Morass- could you plz include scanline algorithm problems like this https://www.codechef.com/problems/LAZER
I was searching for randomization problems, but couldn't find a randomization category here. :( After expanding the categories and searching for "random", I found 9 problems, but I think it deserves its own category.
There are some problems that have very nice randomized solutions, and sometimes they aren't the intended solutions, but I believe randomization can sometimes be very powerful and interesting.
If I remember some of them I'll add them here. Kindly if anyone has such problems, post them too.
https://mirror.codeforces.com/blog/entry/51244
https://mirror.codeforces.com/blog/entry/69496
https://mirror.codeforces.com/blog/entry/66444
https://mirror.codeforces.com/blog/entry/71097
https://mirror.codeforces.com/blog/entry/61205
https://mirror.codeforces.com/blog/entry/62602
On a separate note, I believe it'll nice if each topic has its list of tutorials too. Most have easily-reachable nice tutorials, but some do not, and some tutorials are much better than others, so I believe it'll be nice if there's like a list of high-quality tutorials per topic, along with short comments if needed.
Can you please arrange them in groups? for example, graphs, geometry etc.
FFT Questions :
https://mirror.codeforces.com/problemset/problem/1096/G
https://mirror.codeforces.com/problemset/problem/632/E
https://mirror.codeforces.com/problemset/problem/1251/F
I found these nice ..
You may add these too
Commenting to save the blog! Thank you!
You can add it to favorites, just click the star at the end of the blog (near the contribution count).
thanks a ton :)
Thanks a lot for these! These are really useful for beginners like me.
hi and thanks for amazing blog post -Morass-. can you explain your segment Tree solution for 915E please?
whats is total number of problems here? Has anybody counted ?
2870
"Unable to parse markup [type=CF_MARKDOWN]"- Is this the actual post or is the link broken??
Hey ye: no idea what is wrong (not much verbose x( )
Here is the source to the post -- so you might either refer to it, or if anybody sees any visible failure — you can ping me and I'll try to fix x)
Have nice day ^_^
The link gives me this error -_-
Error, this is a private paste. If this is your private paste, please login to Pastebin first.
Could you solve it, please?
yayx -- Might be hopefully fixed :D
Thank you for your response got the pastebin link
The problems aren't enclosed properly in the spoiler boxes currently. -Morass-
Isn't there a topic for Heavy-Light-Decomposition? I haven't found it
I can't think of the solution to the problem "CODESPTI" in topic "topo". Could someone tell me how to do it?
Thanks!
how to approach graph modeling problems?
That's really great :)
Great problemset
Thanks
some problem links are not working....
thanks
d