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kozliklekarsky's blog

Problem of the Year
By kozliklekarsky, history, 23 months ago, In English

Hello Codeforces,

This year certainly was one of the years of all time. With it coming closely to an end, I think it would be worth to reminisce and applaud the greatest contemporary problem setting creations. Which problem made you your year?

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23 months ago, # |
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1758D - Range = √Sum was the problem that surprised me the most this year — and I still don't understand my own two-pointers solution(182519051) on it!

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    23 months ago, # ^ |
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    What were you surprised by in this problem?

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      23 months ago, # ^ |
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      The fact that A-D were all mid constructives that round

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23 months ago, # |
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1673F — Anti-Theft Road Planning was the problem that made my year.

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23 months ago, # |
  Vote: I like it -95 Vote: I do not like it

I don't have a link but:

Se da un sir de cifre separate prin operatori '*', '+', '-', '/', '^', '&', 'XOR', '!' '|'. Avand voie sa faci maxim K interschimbari intre operatori, aflati valoarea maxima a expresiei.

Marinush

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23 months ago, # |
  Vote: I like it +42 Vote: I do not like it

This one

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23 months ago, # |
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1687F - Koishi's Unconscious Permutation Certainly the most complicated g.f. tasks I have solved so far.

I also like ARC145F Modulo Sum of Increasing Sequences / 147F Again ABC String.

Sorry that I haven't solve much this year.

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23 months ago, # |
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1748D - ConstructOR

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23 months ago, # |
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Problem with Random Tests. randomized algorithms

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23 months ago, # |
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1634B - Fortune Telling, 1740G - Dangerous Laser Power, 1740H - MEX Tree Manipulation, 104094H - One-dimensional Game.

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23 months ago, # |
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If you asked me what would be the problem that encapsulates this years the best, I would certainly answer this one. Sadly the statement is in romanian, so the broader audience won't understand it.

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23 months ago, # |
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I think maspy's D — Simultaneous Sugoroku deserves this place. Too beautiful problem.

It somehow reminds me of the dragon curve (paper folding).

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23 months ago, # |
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DMOPC '21 Contest 9 P4 — Ace of Diamonds

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23 months ago, # |
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I always look forward to seeing the blog "favorite problems of years X" :) I had so much fun solving so many different tasks through this year!

Here are some problems which made me very happy this year:

  • E. >= K it looks complex at first and it's easy to get lost in the implementation, but with a proper insight it's surprisingly simple

  • G. Anti-Increasing Addicts this just made me laugh out loud when I got AC

  • CEOI 2022 abracadabra the main idea is very cute, I saw it one Slovak problem once and I wished to see it again. My wish came true month later :)

  • E. Colorful Operations this problem looks standard at first but it has one surprisingly very cute idea which made me smile when I figured it out.

the cute idea

I'm sure there are more problems which are worth mentioning. I'll update the list when I'll remember them :)

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23 months ago, # |
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USACO January Gold P3 — Tests for Haybales

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23 months ago, # |
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Disclaimer: none of these is on this list necessarily because they are particularly beautiful in some algorithmic way.

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23 months ago, # |
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1753C - Wish I Knew How to Sort.

This is definitely the most beautiful problem I've solved this far.

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23 months ago, # |
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23 months ago, # |
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Yet another vote here for CEOI 2022 Abracadabra.

minor problem spoiler
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23 months ago, # |
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AGC057 C, AGC 057 D, AGC 058 D

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23 months ago, # |
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Although I really loved God of War Ragnarök, it turned out Elden Ring won this year.

Thanks to all problemsetters for creating beautiful tasks in this year!

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23 months ago, # |
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1729E — Guess the Cycle Size

An unusual type of problem, there is no solution that is 100% correct.

Also 1729 is the Hardy-Ramanujan Number, very well known in mathematics

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23 months ago, # |
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1715F —— Crop Squares

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23 months ago, # |
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C1,C2. Sheikh I would appreciate this problem , I tried so many different approaches and made many submissions and every time I was amazed to what test case it failed and I learned so many things too.

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23 months ago, # |
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https://loj.ac/p/3626

You have a tree, and each point has a point weight $$$v_i$$$ . You need to find the determinant of a given matrix.

Hint
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    23 months ago, # ^ |
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    Oops!It came out in 2021's winter.But it's really a interesting problem.

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23 months ago, # |
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G. Kirill and Company

F — Pay or Receive

E. Black and White Tree

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23 months ago, # |
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1705E - Mark and Professor Koro

1715F - Crop Squares

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23 months ago, # |
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1771C - Hossam and Trainees made the year.

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23 months ago, # |
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1737D — Ela and the Wiring Wizard

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23 months ago, # |
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The best problems I've seen this year are :

1750F - Majority

Spoiler

1637G - Birthday

Spoiler

1687E - Become Big For Me

Spoiler

Funnily enough, while looking through my solves, far too many good problems were made just 2 months before 2022.

My favorite problems just before 2022

1586E - Moment of Bloom

1586F - Defender of Childhood Dreams

1586G - Omkar and Time Travel

1610F - Mashtali: a Space Oddysey

1615F - LEGOndary Grandmaster

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23 months ago, # |
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I really liked solving this problem 104067H - Расстановка тыкв. Also this C is nice also 1761C - Построение множеств

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23 months ago, # |
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CF :
1646E - Power Board
1736C2 - Good Subarrays (Hard Version)
1691F - K-Set Tree
1700E - Serega the Pirate
1733E - Conveyor
1743F - Intersection and Union

Atcoder :
ABC261Ex⠀--⠀Game on Graph
ABC281G⠀--⠀Farthest City
ABC272G⠀--⠀Yet Another mod M
ABC270G⠀--⠀Sequence in mod P
ABC243G⠀--⠀Sqrt
ABC268E⠀--⠀Chinese Restaurant (Three-Star Version)
ARC150C⠀--⠀Path and Subsequence
ABC263E⠀--⠀Sugoroku 3
ABC282G -- Similar Permutation

DMOJ :
YAC3P2⠀--⠀Work Experience

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23 months ago, # |
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1771B - Hossam and Friends

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23 months ago, # |
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1773A — Amazing Trick

1624G — MinOr Tree

ABC273E — Notebook

ABC268E — Chinese Restaurant (3-Star Version)

ABC262E — Red and Blue Graph

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23 months ago, # |
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https://mirror.codeforces.com/contest/1695/problem/D2

My favorite one.

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23 months ago, # |
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There were many great problems that I solved this year. Here are some that I liked the most:

Key observation
How I did it
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23 months ago, # |
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non-mentioned but very very cool problems

1667C - Half Queen Cover

1628C - Grid Xor

1654F - Minimal String Xoration

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23 months ago, # |
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For me it's no doubt Fake Plastic Trees 2 from Winter Petrozavodsk Day 2. It looked like a completely unsolvable problem, so it was so satisfying to finally solve it, I felt like a genius

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23 months ago, # |
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Doremy's Pegging Game — The idea of the solution is really nice.

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23 months ago, # |
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Changed my mind, this is the greatest problem

1736B - Playing with GCD

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23 months ago, # |
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ARC 147D CF 1693C

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23 months ago, # |
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1726A. Mainak and Array for the wrong reasons. Common mistake would be printing the difference between the maximum and minimum element. The mistake gave an answer of "996" (72 hours a week) instead of "962" (18 hours a week). So we made the servers work an "extra 54 hours" to process the influx of incorrect solutions

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23 months ago, # |
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For me the greatest problems were :

1762D - GCD Queries

1733D2 - Zero-One (Hard Version)

And those problems were nice and I enjoyed solving them although they are a bit easy:

1697D - Guess The String

1772F - Copy of a Copy of a Copy

1713D - Tournament Countdown

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23 months ago, # |
  Vote: I like it +10 Vote: I do not like it
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