thanhchauns2's blog

Codeforces Round #842 (Div.2)
By thanhchauns2, history, 23 months ago, In English

Hi Codeforces!

Igorfardoc, Vladithur, Alexdat2000, GlowCheese, DeMen100ns, SPyofgame and me (spelling "thanh-chau-n-s-2") are delighted to invite you to participate in Codeforces Round #842 (Div. 2). This round will be rated for all participants with a rating lower than 2100.

This contest is brought to you by

Special thanks to:

Edit: there will be $$$2$$$ packages for two participants in Vietnam, the highest score and the luckiest. You have to set your region to Vietnam to be qualified.

The score distribution is $$$500-1000-1500-1750-2250-3250$$$.

Hope to see you in the final standings!

Editorial is out.

Congratulations to the winners:

Div.1+2 Div.2
1 arvindf232 drizzlo
2 Hyperbolic jiangly_fan_fan_fan_fan
3 drizzlo BedzieMagikZa2Lata
4 jiangly BeautifulChicken
5 Um_nik AE-3803

And the first solver for each problem:

A B C D E F
Div.1+2 dapingguo8 tourist youknowiknowyouknow A_G nok0 jeroenodb
Div.2 celestialcoder 1024mb youknowiknowyouknow MIOC69 cmk666 drizzlo
  • Vote: I like it
  • +593
  • Vote: I do not like it

Comments Comments (206)
| Write comment?
»
23 months ago, # |
← Rev. 3   Vote: I like it +29 Vote: I do not like it

As a slave~ setter, wishing you all peace, joy, and unconditional love at Christmas and always. And of course, with ++rating :Đ

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    As a tester, love you SPyofgame

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      love you SPyofgame orz

      → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
          Vote: I like it +5 Vote: I do not like it

        As a person that likes the colour cyan, this post is just pleasing for my eyes.

        → Reply
        • »
          »
          »
          »
          »
          23 months ago, # ^ |
            Vote: I like it +35 Vote: I do not like it

          As a tester, I'm only GREEN.

          But they promote me to...cyan! Thanks a lot. >_<

          Spoiler
          → Reply
          • »
            »
            »
            »
            »
            »
            23 months ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            You are a green with the power of a grandmaster, and that is something to look up to.

            Spoiler
            → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    As a tester [insert joke]. I liked the problems as I've put some effort in upsolving, hope you'll enjoy them as well.

    → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    It's hard to increase your rating by only one. ++rating

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      I did that. actually

      → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it +45 Vote: I do not like it

      prvocislo: And I took that personally.

      → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
          Vote: I like it +8 Vote: I do not like it

        lol and then they removed cheaters and rating++ was gone :')

        → Reply
        • »
          »
          »
          »
          »
          23 months ago, # ^ |
            Vote: I like it +15 Vote: I do not like it

          Nah because it was ++rating++, the bonus score is the gift from the main route mission to LGM.

          → Reply
»
23 months ago, # |
  Vote: I like it +2 Vote: I do not like it

I am a setter.

→ Reply
»
23 months ago, # |
  Vote: I like it +3 Vote: I do not like it

As a do-nothing-setter, gluck everyone!

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    As a do-nothing-setter, I found another do-nothing-setter and that's pretty POG.

    → Reply
»
23 months ago, # |
  Vote: I like it +19 Vote: I do not like it

As a tester, Merry (late) Christmas everyone!

→ Reply
»
23 months ago, # |
  Vote: I like it +21 Vote: I do not like it
Hi!
→ Reply
»
23 months ago, # |
  Vote: I like it +21 Vote: I do not like it

As a tester,this is my first time.Also,i want tell you something important

Spoiler
→ Reply
»
23 months ago, # |
  Vote: I like it +19 Vote: I do not like it

cyanforces

→ Reply
»
23 months ago, # |
  Vote: I like it +3 Vote: I do not like it

As a tester, I can guarantee that you'll find interesting tasks in this round! GL & HF.

→ Reply
»
23 months ago, # |
  Vote: I like it +3 Vote: I do not like it

as a tester, nya

→ Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

Cyan Supremacy

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +8 Vote: I do not like it

As a tester, this contest is worth participating and learning how to brainstorm ideas efficiently. Good luck and have fun in the last days of 2022!

→ Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

omg cyan round

→ Reply
»
23 months ago, # |
  Vote: I like it +85 Vote: I do not like it

Regardless of my experience testing this round, the problems are good.

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

omg cyan round :)

→ Reply
»
23 months ago, # |
  Vote: I like it +26 Vote: I do not like it

As a cyan tester, I recommend partipating

→ Reply
»
23 months ago, # |
  Vote: I like it +17 Vote: I do not like it

as a tester, this round is better

→ Reply
»
23 months ago, # |
  Vote: I like it +11 Vote: I do not like it

Hoping for a problem E solvable for me (to keep my current rating)

→ Reply
»
23 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Please downvote me

→ Reply
»
23 months ago, # |
← Rev. 4   Vote: I like it +14 Vote: I do not like it

Round of specialists! (NY's magic)

→ Reply
»
23 months ago, # |
← Rev. 4   Vote: I like it +21 Vote: I do not like it

I enjoyed the "you" trick and the hidden text (doesn't work on the dark theme).

→ Reply
»
23 months ago, # |
  Vote: I like it +9 Vote: I do not like it

CYAN IS EVERYWHERE!

→ Reply
»
23 months ago, # |
  Vote: I like it +11 Vote: I do not like it

cyan round, so maybe i've got a chance

→ Reply
»
23 months ago, # |
  Vote: I like it +26 Vote: I do not like it

MikeMirzayanov 😎

→ Reply
»
23 months ago, # |
  Vote: I like it +20 Vote: I do not like it

One of the most visually pleasing announcements!!

→ Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

This round should be named "Specialists Round"

→ Reply
»
23 months ago, # |
  Vote: I like it +11 Vote: I do not like it

omg cyan round

→ Reply
»
23 months ago, # |
  Vote: I like it +7 Vote: I do not like it
great contest will arise tomorrow
→ Reply
»
23 months ago, # |
  Vote: I like it +17 Vote: I do not like it

How about every participant changing their color to cyan for this round ?

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope I don't become green after this cyan round.

→ Reply
»
23 months ago, # |
  Vote: I like it +52 Vote: I do not like it

1000 cyans versus a LGM, just as in the old days.

→ Reply
»
23 months ago, # |
← Rev. 3   Vote: I like it +1 Vote: I do not like it

Hocus Pocus Abrakadabra , turn me into cyan

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Viet Nam contest legoo

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Cyan_Forces ✪ω✪

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +3 Vote: I do not like it

wow, Filled with cyan on all sides

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

cyanforces

→ Reply
»
23 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Help -is-this-fft- finish off 2000 problems.

→ Reply
»
23 months ago, # |
  Vote: I like it +19 Vote: I do not like it

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

The most cyan round ever. It will be interesting!

→ Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

so~so~so~so~so~green~ ovo!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Why is everyone cyan now?

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Time for VietnamForces!!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +8 Vote: I do not like it

Specialist Forces

→ Reply
»
23 months ago, # |
  Vote: I like it +13 Vote: I do not like it

Today I feel Vietnamese.

→ Reply
»
23 months ago, # |
  Vote: I like it +5 Vote: I do not like it

Cool fact that div made by Russians and Vietnamese while im Vietnamese but born in Russia... Great job guys!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

Nice editing for last point.

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Div2 finally, its my time to shine!!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope to get Master again!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I love you!

→ Reply
»
23 months ago, # |
  Vote: I like it +27 Vote: I do not like it

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

is the contest unrated?

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Added that it's rated for everyone with rating < 2100.

    → Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

how to calculate the contribution?

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I pressed on LG "you", but it shows me grey :|

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

THE ONE PIECE IS REAL!!!

→ Reply
»
23 months ago, # |
  Vote: I like it +17 Vote: I do not like it

DeMen100ns, what the ..?

→ Reply
»
23 months ago, # |
  Vote: I like it +26 Vote: I do not like it

As a tester, I became cyan.

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +9 Vote: I do not like it

I hope to become cyan in the cyanforces

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

just made it in time (i ran from the bus station), hopefully i won't turn cyan

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

excited!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

All the best guys....

→ Reply
»
23 months ago, # |
  Vote: I like it +11 Vote: I do not like it

Speedforces!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

Permutation forces

Loved it

→ Reply
»
23 months ago, # |
  Vote: I like it +8 Vote: I do not like it

Task F is really awesome!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

As a participant I love Vietnamese Contest! (tks for free rating)

→ Reply
»
23 months ago, # |
  Vote: I like it +16 Vote: I do not like it

Permutationforces. I love it.

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

Any ideas for C?

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I was also stuck at C , what was your approach?

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Nothing special, was implementing whatever was coming to my mind

      → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        What did you guy stuck on C ? You can check for da editorial, but you can also give your question here and I will reply :v

        → Reply
»
23 months ago, # |
  Vote: I like it -14 Vote: I do not like it

stupid speedforces

→ Reply
»
23 months ago, # |
  Vote: I like it +13 Vote: I do not like it

Why are there so many permutation problems?

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

From expert to pupil. I don't understand why this is happening...

→ Reply
»
23 months ago, # |
  Vote: I like it -11 Vote: I do not like it

A<F

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I am almost sure that 99% people simply saw the testcases and returned n-1 :P for A

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it +10 Vote: I do not like it

      Anyone with > 0.5 braincells can see that n! = n * (n — 1)!

      → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      is this not correct??

      → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        yes that is, but no one derived it I meant.

        → Reply
        • »
          »
          »
          »
          »
          23 months ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          i have 10 min i doesn't see that it ask for max i think it ask for min i tried binary search but when loking at sunmission rate i rewrite then just a second to solve k! + (k-1)! = (k+1)(k-1)! k-1 is best choice

          → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    F>A

    → Reply
»
23 months ago, # |
  Vote: I like it +28 Vote: I do not like it

permutationForces.

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Why would you do that??? So many problems on permutations! It's just ridiculously disrespectful for those who suck in this theme!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Now its time to chnage the color After very long time

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Hate permutations, hate sortings, hate myself. Goodbye chance to become pupil :(

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    +1 hate permutation problems, therefore hate this contest...

    → Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I wonder how many people actually proved their solution for A.

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    it was kinda easy to prove .

    take the (x-1)! common from (x ! + (x-1)!) which will end up giving this equation . (x-1)! * (x+1). take a x such that x+1 = k .

    → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    It was clear to me that if there is a solution it should be k-1 to obtain the maximum number of factors from the factorial. To prove that this answer always works, I did a simple proof.
    for x = k — 1
     x! + (x — 1)! = (x — 1)! * (x + 1) = (k — 2)! * k

    → Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

how to solve C anybody ?

→ Reply
»
23 months ago, # |
← Rev. 3   Vote: I like it +2 Vote: I do not like it

Hi guys I have uploaded editorial solutions here — check.

have uploaded A,B,C for now and would upload D in a few mins :) let me know if you find these helpful :)

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Permutation Round!!!

BTW, how to solve D?

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Permutation with inversion number can only be in form

    Unable to parse markup [type=CF_MATHJAX]

    .

    So the basic idea is to try each $$$x$$$, there are $$$n-1$$$ possibilities.

    When changing your permutation from $$$p$$$ to $$$s$$$, it is equal to swapping $$$x, x+1$$$ in $$$p$$$ and sorting $$$p$$$. It is well known that the minimum swap required to solve $$$p$$$ is

    Unable to parse markup [type=CF_MATHJAX]

    (p after $$$x, x+1$$$ swapping). So we need to find $$$x$$$ that maximizes the number of components after $$$x, x+1$$$ swapping.

    Another conclusion is that if $$$a$$$ and $$$b$$$ are in the same component, then swap $$$a, b$$$ adds one component. Otherwise, if $$$a$$$ and $$$b$$$ are in different components, then swap $$$a, b$$$ decreases the number of components by $$$1$$$. So we need to check whether there exists an $$$x$$$ such that $$$x, x+1$$$ are in the same component~

    Besides, how to solve B???

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      Best possible arrangement is for any N is 1 2 .... N , in sorted order.

      You just need to find the longest best arrangement possible

      For eg : N = 5 , A[] = [ 1 , 3 , 2 , 5 , 4 ] , the best possible arrangement that is already possible is taking [1 , 2] & not perform any operation on them as they are in longest sorted order & perform the operations on the remaining elements, taking the ceil of [Remaining elements / K] as the answer.

      → Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

How to solve B, please??? A+C+D <= 40min. Unfortunately, I have no idea to solve B in the left time. I have to admit I am stupid.

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Find 1 in the permutation. On the right of it, find 2. Continue this process until you can't find the larger number. ( n — numbers you've found )/k is the answer (round up).

    → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    check editorial here — click

    → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    Yes, scan

    Unable to parse markup [type=CF_MATHJAX]

    in LEFT->RIGHT direction. E.g. dynamic regex: /\b(??{ $s })\b(?{ $s ++ })(*F)/
    → Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Please help in problem D My idea was to find minimum moves to make the array equal to the sorted permutation in which exactly one pair of adjacent elements is interchanged This gave WA

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    idea is the same just you have to make component s if the adjacent is not in the same component at all first we find all then all +1

    → Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

For Problem D , I tried with finding cycles for shifting/swapping. Then was trying something based on the cycle size. Something similar to min swaps needed to sort an array. but couldn't get it. Any ideas?

One observation I had was : to have exactly 1 inversion, we need i and i + 1 to be swapped , rest entire array needs to be sorted.

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You were correct in your approach and observation.

    Let x — min swaps required to sort the array. You just need to check if the cycle has a consecutive number then the answer is x-1.

    Else answer is x+1.

    → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    yes thats the main observation after that you have to grp them (components) type then just find the ans

    → Reply
  • »
    »
    23 months ago, # ^ |
    ← Rev. 2   Vote: I like it +8 Vote: I do not like it

    Let $$$x$$$ be the min swaps to sort the array, let if $$$i$$$ and $$$i + 1$$$ are in the same cycle, you need $$$x - 1$$$ swaps to get the array where the only inversion is

    Unable to parse markup [type=CF_MATHJAX]

    , otherwise you need $$$x + 1$$$ swaps. (can't really prove it tho)
    → Reply
»
23 months ago, # |
← Rev. 3   Vote: I like it +2 Vote: I do not like it

Problem A is very bad for the CP contests, it is better for math competitions.

It is bad because it doesn't check any skills and knowledge because it was worth to try just $$$k-1$$$ after looking at the sample tests.

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

First time ranked top100 in div2. Hope for no FST!

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Any hints for D?

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    i think this is a hint: answer is min swaps to sort + 1 or min swaps to sort — 1

    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      What I was able to analyze is that eventually our answer would look like 1.2.3.4...i+1.i....n So yes the answer should be the swaps to sort + 1 or -1 depending upon can we make the above state just before the last swap to sort. Now IDK whether this is correct or not but if we have some i which is at position(i-1) or (i+1){1 based positions} then we'd subtract 1 otherwise we'd add 1. Is the above correct? Please give reason as well

      → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Incorrect.

        1
5
3 4 5 2 1

        2 in position 3. But answer is 4. Because 2 and 5 (in position 3) belongs to different cycles (1 3 5) and (2 4). So you cannot in two moves get 1 2 4 3 5.

        If you'd get cycle likee 2 5 x x 1 (two consecutive numbers in one cycle) then you can in one move get 2 1 x x 5.

        → Reply
        • »
          »
          »
          »
          »
          23 months ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          the positions are 1 based but u gave 0 based.

          → Reply
          • »
            »
            »
            »
            »
            »
            23 months ago, # ^ |
            ← Rev. 3   Vote: I like it 0 Vote: I do not like it

            Ok, then that

            1
8
1 7 5 8 2 6 3 4

            You got cycle x 7 5 x 2 x 3 x, so you can in two moves do

            x 7 5 x 2 x 3 x
            x 3 5 x 2 x 7 x
            x 3 2 x 5 x 7 x

            So you need to substract one, but there is no such i in i-th or (i + 2)th position

            Reason: all cycles can be treated indepenedent, so in cycle with len l need do l - 1 moves to sort cycle, and if in cycle exists two consecutive numbers then you need l - 2 moves to get one inversion in that cycle.

            → Reply
      • »
        »
        »
        »
        23 months ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        Incorrect

        1
6
6 5 3 4 1 2

        no such i but we'd subtract 1

        we cannot guarantee that the i is the inversion by just looking at this, this is actually my proposed solution in the contest :/ which i got Wrong Ans2

        Reason: idk, have some counter case

        → Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it
    Hint1
    Hint2
    Hint3
    → Reply
    • »
      »
      »
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Yo, could u check my soln once? the one i wrote above

      → Reply
  • »
    »
    23 months ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    Hint 1: A permutation has one inversion if and only if the permutation is

    Unable to parse markup [type=CF_MATHJAX]

    for some $$$i$$$.

    Hint 2: The minimum number of transpositions from a permutation $$$\pi$$$ to change it to the identity is $$$n-c$$$ where $$$c$$$ is the number of cycles in the permutation.

    hint 3: The distance between two permutations is the distance between the permutation given by the composition of first with inverse of second, and the identity permutation.

    hint 4: count number of cycles $$$c_i$$$ in $$$p$$$ composed with

    Unable to parse markup [type=CF_MATHJAX]

    for all i in O(n) time. The answer is

    Unable to parse markup [type=CF_MATHJAX]

    → Reply
  • »
    »
    23 months ago, # ^ |
    ← Rev. 3   Vote: I like it 0 Vote: I do not like it

    Just check out this. All Will be clearminimum-number-swaps-required-sort-array Secondly check if there is any x+1=y element in the cycle.

    → Reply
»
23 months ago, # |
  Vote: I like it +7 Vote: I do not like it

Is problem C a little difficult to write? I wrote it twice.

Besides, the problems of this competition is very interesting.

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    You know, it's permutationspecialistforces. :)

    → Reply
  • »
    »
    23 months ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    I dunno, my solution was straightforward and simple :think:, maybe you can hack me I guess

    But as a setter, can you give detail for the issues you have to deal with during the contest ?

    Linear Solution for Problem C
    → Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

WA on test 2 in problem C... can anybody help (188113413)?

→ Reply
»
23 months ago, # |
  Vote: I like it +7 Vote: I do not like it
  • Permutation of B Solved
  • Permutation of C Solved
  • Permutation of D Fucked Up Man
→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +19 Vote: I do not like it
Spoiler
→ Reply
»
23 months ago, # |
  Vote: I like it +132 Vote: I do not like it

Is Um_nik stronger than 1000 cyans? Let's find out! Screencast with commentary

→ Reply
»
23 months ago, # |
  Vote: I like it -28 Vote: I do not like it

Problems A, B, C, D, and E were all very straightforward and meaningless to solve. With all respect to the authors, it was one of the worst contests that I participated in.

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I wish I could say this in some rounds.

    → Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

fuck this system bro i swear to god half of c submissions from youtube channels

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I hope all of those skipped! If you can make a blog as you spotted those similar solutions. Go on, Do!

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

finally cyan in the cyanforces <3

→ Reply
»
23 months ago, # |
  Vote: I like it +24 Vote: I do not like it

Ratings updated preliminarily. We will remove cheaters and update the ratings again soon!

→ Reply
»
23 months ago, # |
  Vote: I like it +6 Vote: I do not like it

permutation_forces

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +12 Vote: I do not like it

So happy today !!! Became Specialist for the first time !!

Thanks a lot for the contest

I m shocked to observe that I somehow solved C in O(N)

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

Became Cyan (finally) in the Cyan round!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

I would like to point out that the first to address F in Div.2 should be drizzlo. derekFeng's rating is 2746, and I think it may have been New Year's magic that led to an oversight on the part of the blog writers.

Updated:

Already fixed at light speed! Thanks again to the author for preparing such a great round and for the attention to feedback!

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Short Statements = Beautiful

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Can anyone help me figuring out why I'm getting runtime error for problem C on test case 7.I'm trying from 3 hours still not able to figure it out.Your time will be worth a lot.Thanks in advance . Here's my code 188125909

→ Reply
  • »
    »
    23 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Your code is such a mess. You can Google your exit code (-1073741819 )on test 7, it is something about memory access violation. My !guess! is x--; q[i]=*x; s.erase(x) Or x--; k.erase(x); p[i]=*x;

    But I haven't tried to fully understand what your program is doing

    → Reply
»
23 months ago, # |
  Vote: I like it +16 Vote: I do not like it

One of my favorite rounds, all of the problems have short statements and very clean solutions. I hope you guys author more rounds in the future!

→ Reply
»
23 months ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

.

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I became cyan for the 7th time. Thanks for this contest, created by 7 'cyans'.

→ Reply
»
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Why are the top 2 in division 2 new accounts?

→ Reply
»
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it

me sitting happy with +0 delta.

→ Reply
»
22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

MikeMirzayanov Hi, I received this message: Your solution 188082997 for the problem 1768C significantly coincides with solutions csegura/188082997, Sahil9259/188104072, UnRiVaLeD__/188104217, Frieza_Comeback/188106033, ashu1509goel/188107094, atharv_soni/188109171, bs_biswa/188109314, POSEIDON_RAGNAROK/188119467, soumabha_12/188120764. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details.

I see that I was not skipped because I was the first one to submit the code; Good job in identifyng the copy. I don't use any online system, so it was leaked through the codeforces system. By the time that my code was leaked, it seems that the only person in my room that had closed the problem was coderpro2, so, if this is confirmed, in my opinion, actions against this account should also be taken.

→ Reply
»
22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Got WA, can somebody help me? I still can't figure out the testcase which my code fails on. (188511376)

→ Reply
»
22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I'm having a serious trouble solving Problem F with Java 8.I believe my code is essentially the same as the description in tutorial, but all I got is TLE in case 24/25. Is there anyone ACed this problem with Java? Or can someone tell me why my code is so slow?
Here's my code:188557390 Sorry for the trouble

→ Reply
  • »
    »
    22 months ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    solved by fixing multiple mistakes. turns out I understand nothing of the solution :)

    → Reply