Denisson's blog

Codeforces Round #444 (Div. 2)
By Denisson, history, 6 years ago, translation, In English

Hello Codeforces!

Round will start on Thursday, 3 November in 19:05 MSK.

Tasks are prepared by Anton Garder (.tx) and me, Shpakovskiy Denis (Denisson). Thanks to 300iq, Glebodin, FalseMirror, cdkrot, Arpa, Starcall for testing problems, vintage_Vlad_Makeev for coordination and translation, MikeMirzayanov for Codeforces and Polygon platforms.

You will have six problems to solve in 2.5 hours.

Hope you will enjoy problems. Good luck to all!

Scoring: 500—1000—1500—2000—2500—3000

We want to apologise for mistakes in problem statements that led to round being unrated

Editorial.

  • Vote: I like it
  • -479
  • Vote: I do not like it

Comments Comments (270)
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6 years ago, # |
  Vote: I like it -120 Vote: I do not like it

RATED ???

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

3rd october??? :P

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6 years ago, # |
  Vote: I like it -31 Vote: I do not like it

hi guys im trying to have the worst contribution possible on this sit Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?Is It RaTeD?

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    6 years ago, # ^ |
      Vote: I like it -36 Vote: I do not like it

    Now no comments :p

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    6 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    not for me, bro

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    6 years ago, # ^ |
      Vote: I like it +27 Vote: I do not like it

    guys you just got me from contribution -10 to -9 please downvote don't upvote im trying to have the trashiest contribution!!!

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      6 years ago, # ^ |
        Vote: I like it -6 Vote: I do not like it

      I think he deliberately said that he wanted to be downvoted in order to wangle our upvotes :)

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        6 years ago, # ^ |
          Vote: I like it +4 Vote: I do not like it

        no i really mean to be downvoted

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    6 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    well you have more contribution than the problemsetter...

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6 years ago, # |
← Rev. 2   Vote: I like it -39 Vote: I do not like it

.

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6 years ago, # |
← Rev. 2   Vote: I like it -29 Vote: I do not like it

Why always me?

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6 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Thanks a lot to Denisson for providing us with this kind of enjoyable moments. And good luck to All who like coding without worrying about if IT IS RATED or NOT. :)

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6 years ago, # |
  Vote: I like it -6 Vote: I do not like it

UNRATED ?

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6 years ago, # |
  Vote: I like it +40 Vote: I do not like it

In april 2016 something life-changing happened with Denisson =)

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6 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Super excited to give this contest. Codeforces, you made my day! Thank you so much!

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6 years ago, # |
  Vote: I like it +2 Vote: I do not like it

Would be great if this contest features the number "4", celebrating the "444th" Div2 round.

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Palindromic Contest!444

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6 years ago, # |
← Rev. 2   Vote: I like it -19 Vote: I do not like it

Why people are downvoting me i can't understand:(

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    6 years ago, # ^ |
      Vote: I like it -12 Vote: I do not like it

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You are allowed not to mind about 10-100 downvotes: because 10 downvotes in a single comment is not so important in most people’s life.

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6 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

Unrated!

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6 years ago, # |
  Vote: I like it +2 Vote: I do not like it

In the C,the pos.2 & pos.5 color?

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6 years ago, # |
  Vote: I like it +138 Vote: I do not like it

Am I the only one that doesnt like the contest ? glad this is unrated for me so i dont have to solve C :/

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Does problem C promises that color 1's opposite is color 4 and so on as sample input?

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6 years ago, # |
  Vote: I like it +35 Vote: I do not like it

1 ) Problem Statements are not clear 2 ) Too many pop ups in between contests 3 ) Codeforces is not responding sometimes. 4 ) For problem C ,Image was not correct earlier

I thinks it is better to unrate this contest rather than unfair.

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    OH, I was wondering why my code did not work. Because I wrote it completely based on picture. That is annoying -_- EDIT: Picture is not wrong, but without clarification I did something else/not what the problem wanted.

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6 years ago, # |
  Vote: I like it +27 Vote: I do not like it

What the hell is happening? A lot of problem with problem statement. "You can remove no digits (that is, leave it as is)." This cost me 5 WA. Important information of problem C is given after 1:30 hr "You should do exactly one rotation of cube" "There was an issue with picture in notes for problem C, now it's fixed" . Is it a joke?

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6 years ago, # |
  Vote: I like it +44 Vote: I do not like it

I wish I wouldn't have participated in this :/

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6 years ago, # |
  Vote: I like it -6 Vote: I do not like it

I don't know what is Rubik's cube, I didn;t use it before. Am I suppose to know such things also before a contest ?

What is a rotation ? And how did the author make a mistake with the image ? That is the only hope for peoiple like me who dont know this stupid game.

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    The game is quite popular. It's also not stupid.

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      6 years ago, # ^ |
        Vote: I like it -29 Vote: I do not like it

      But if someone isin't aware of it, should they fuck themselves and loose rating ? Don't u think if this happens with u(for some other game), it is very unfair ?

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        6 years ago, # ^ |
          Vote: I like it +13 Vote: I do not like it

        I go to wikipedia and read about the game. It's not really the author's job to make sure we all know every game on earth. Isn't it kinda expected that we'll know tic tac toe?

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    6 years ago, # ^ |
      Vote: I like it +27 Vote: I do not like it

    What if you were asked a question on some algorithm which you don't know but is very famous. Do you still blame the author that you don't know and so bad question?? It seems yes.

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Well, your point is a bit orthogonal, as knowing algorithms is directly related to CP. However, I think the author isn't wrong to include a problem on something as well known as rubiks cube. In the past we had problems about Matryoshka dolls too.

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6 years ago, # |
  Vote: I like it +9 Vote: I do not like it

Very bad contest. Server HTTP 500 many times. The weird Rubik never played before.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

An occupy contest :|

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6 years ago, # |
← Rev. 2   Vote: I like it +38 Vote: I do not like it

In Problem C , Defination of a rotation could be given by author , we are not CHAMPIONS in rubrik game like you Denisson

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6 years ago, # |
← Rev. 2   Vote: I like it -18 Vote: I do not like it

Great contest for me first time solved 2 questions:)

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6 years ago, # |
  Vote: I like it -6 Vote: I do not like it

What the fuck????

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6 years ago, # |
  Vote: I like it +35 Vote: I do not like it

Good contest (no)

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Unlucky

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6 years ago, # |
  Vote: I like it +18 Vote: I do not like it

Oh fuck..I spent almost 1 and half hour on problem D figuring out how the hell can one solve it in given time limit.

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6 years ago, # |
  Vote: I like it +24 Vote: I do not like it

I think more clarity should be given in implementation based problems like C.

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6 years ago, # |
  Vote: I like it +59 Vote: I do not like it

My code for C was more than 200 lines long and now the contest is unrated...ARE YOU FUCKING KIDDING ME ?!?!??!?!

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Are you sure, that your code will pass system tests ? =)

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      You and haleyk100198 are probably right but it still hurts too much.

      I should be thankful I was gonna lose rating but now I'm good.

      :)

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        6 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I think you still need to submit your code =)

        I will look into your implementation after contest ends. It is interesting to compare your solution with mine =)

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          6 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          My solution isn't done yet but I can send you what I wrote it isn't full but the idea is very clear.

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    6 years ago, # ^ |
      Vote: I like it +30 Vote: I do not like it

    Well, if you think positively, long implementation codes usually get randomly screwed by test cases 100+ ...

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6 years ago, # |
  Vote: I like it +17 Vote: I do not like it

It's been a long time since I've been in the top 100, and now, unrated... :(( :((

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6 years ago, # |
  Vote: I like it +37 Vote: I do not like it

This round is SOOO unprepared. Shame on you.

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6 years ago, # |
  Vote: I like it +13 Vote: I do not like it

Thanks for the wonderful contest without ANY mistakes and troubles.

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6 years ago, # |
  Vote: I like it +18 Vote: I do not like it

When you have an amazing CF once a year, and rounds get unrated once a year :D

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6 years ago, # |
← Rev. 3   Vote: I like it +49 Vote: I do not like it

Cracking 15 solutions, solving A+B+C, going top2

Round would be unrated

TRIGGERED

PS: Sorry room 52 :D

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6 years ago, # |
  Vote: I like it +13 Vote: I do not like it

Great. Skipped class to improve rating! :(

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

For the first time in top300: unrated. SAD!

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    6 years ago, # ^ |
      Vote: I like it +19 Vote: I do not like it

    But it is your first contest, suspicious >.<

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6 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Very bad contest. Long duration contest like this one should have dp and graph problems instead rather than implementation major.

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    6 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    Umm what? There's no such rule like that. I agree that not all problems should be annoying implementation problems, but doesn't mean long contests SHOULD feature graph and dp problems.

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6 years ago, # |
  Vote: I like it +10 Vote: I do not like it

many Announcement for A and C :| unrate for D :|||||

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6 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Dear Denisson and .tx, it was my best contest ever, you know??? I am...heartbroken...

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6 years ago, # |
  Vote: I like it +28 Vote: I do not like it

Salute to the ones who wrote C XD

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    6 years ago, # ^ |
      Vote: I like it -16 Vote: I do not like it

    I don't see what's the problem with C. Why are some guys unhappy with C?

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      6 years ago, # ^ |
        Vote: I like it -8 Vote: I do not like it

      because it doesn't have any algorithms. Just rotate a 2x2 cube. It isn't a problem for codeforces.

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        6 years ago, # ^ |
          Vote: I like it +12 Vote: I do not like it

        I personally feel otherwise. You can see some very fast submission times, which means it's a problem to think about how elegant and short our approach can be. Isn't that useful in CP?

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          6 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          I thought, we are solving olympiad-like problems. They usually include graphs, DP, data structures, even geometry. I can't even give a type to problem C.

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          6 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          But I don't even know how rotations occur in rubik's cube. Isin't the author responsible for explaining that ?

          I guess this game is abstract and should at least be explained to be included in a contest.

          I can prepare some really hardcore physics problems , that would take u 10+ hours to understand.

          Should this start happening >?

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6 years ago, # |
  Vote: I like it +7 Vote: I do not like it

Shitty problems...

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6 years ago, # |
  Vote: I like it +27 Vote: I do not like it

Worst C ever. Thank god its unrated.

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6 years ago, # |
  Vote: I like it +85 Vote: I do not like it

When you don't want to spend time thinking what happens after rotating a cube and instead spend more time doing this: -_-

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    6 years ago, # ^ |
      Vote: I like it +38 Vote: I do not like it

    Don't send solution during contest, even if it's unrated.

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Well, this isn't an solution.

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      6 years ago, # ^ |
      ← Rev. 2   Vote: I like it +31 Vote: I do not like it

      Do you really think someone will copy this long text without error after all this inconvenience?

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      6 years ago, # ^ |
      ← Rev. 2   Vote: I like it +11 Vote: I do not like it

      Aha, sorry for that..... Totally forgot the contest is still ongoing after that unrated announcement

      Though I doubt there is another dull-headed guy like me who is gonna try writing these whole thing :v

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    what the hell is this

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It's only have 6 cases with 3 different ways to rotation and 2 direction each way...

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    6 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    It could be simpler..

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6 years ago, # |
  Vote: I like it +17 Vote: I do not like it

May i ask whether the writer or the testers or anyone involved with the preparation of the contest had even read the problem statements? even the Announcement had grammatical errors!

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

rip

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Many problems to be pointed out there, including unclear statements (at least in English, I'm not sure about the original ones) or extremely scarce range of pretests (I even received "Pretest passed" for problem B even though I misunderstood the problem statement, and well, of course, it got hacked later xD) Hope your next contest would be better.

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6 years ago, # |
  Vote: I like it +15 Vote: I do not like it

I'm in top 100, but I have to say that this round should be unrated even if statement of D was correct...

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6 years ago, # |
  Vote: I like it +14 Vote: I do not like it

Contest held after so many days and then it becomes unrated. Not expected.

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6 years ago, # |
  Vote: I like it +182 Vote: I do not like it

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6 years ago, # |
  Vote: I like it +1 Vote: I do not like it

It is my best rank,but unrated now . T_T. go to sleep now... (midnight)

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6 years ago, # |
  Vote: I like it +4 Vote: I do not like it

i should have become an expert :(

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6 years ago, # |
  Vote: I like it +42 Vote: I do not like it

I'm getting so sick of CF rounds. It seems every time I participate something goes wrong, either during contest or during systest. Every other round is unrated, problems are mostly unimaginative and I wonder why I should devote 2h of my day for such contests. Today's round was another hack round, no knowledge required to be in top20 (just a bad enough room). A's most obvious 'corner case' should've been in the pretests. All C solutions I saw while hacking were hideous, and if the solution was "check all possibilities", it's really bad. This rounds issue wasn't D, it was the whole round. (this comment doesn't concern E and F since I haven't tried them, but just looking at the number of ACs, it seems too hard for a div2 round).

Now excuse me, I'm off to solve some CSAcademy problems.

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    6 years ago, # ^ |
      Vote: I like it -20 Vote: I do not like it

    If you're getting sick, better not compete here anymore, you absolutely don't have to. If you do, you'd better accept that mistakes can be made and respect the effort of the authors. Or don't listen to my advice and be sour... |-)

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      6 years ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      This is not about this particular contest or author (even thought in my earlier frustration it might have sounded differently), it's about how often it is, and that I can rarely just compete uninterrupted on this platform. There is a saying "We critique the things we love, so they could be even better", I love CF and its community and I want it to do good, I was just voicing my frustrations.

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6 years ago, # |
  Vote: I like it +313 Vote: I do not like it

CodeForces judge today:

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6 years ago, # |
  Vote: I like it +1 Vote: I do not like it

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6 years ago, # |
  Vote: I like it +18 Vote: I do not like it

It's time to meme when the rating increase is a dream

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6 years ago, # |
  Vote: I like it +1 Vote: I do not like it

The comment is hidden because of too negative feedback, click here to view it

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6 years ago, # |
← Rev. 6   Vote: I like it +13 Vote: I do not like it

There were many errors in the problem statement (Specially in problem C). But many contestants solve this problems before the clarification. The must have some supernatural power or they are superman.

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    6 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    There are 3 possibilities: 1. They solved these problems based on their own knowledge (about rubiks, cubes, or something similar) 2. They took a guess. Like in Problem C, we could guess the order of the color no. based on the diagrams. 3. If things got too dicey, you can ask the jury. Remember that feature, you'll need it, perhaps even in a real contest.

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Yes we could guess the order of the color number. But how can we guess "You should do exactly one rotation of cube" ?

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        6 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I had to read twice to see whether zero rotations would be allowed, but was able to conclude from the problem statement that it was not. The announcement was not necessary. And in my opinion proper reading is part of the challenge.

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          6 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Yes I agree with you that proper reading is part of the challenge. But how can you understand it is valid to delete no digit form this statement "Her problem is following: for given string, consisting of only 0 and 1, tell if it's possible to remove some digits in such a way, that remaining number is a representation of some positive integer, divisible by 64, in the binary numerical system." ? Is (some==none) gives you a 1 ?

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            6 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            I was only replying to your remark about the cube. Again, proper reading... |-)

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              6 years ago, # ^ |
                Vote: I like it 0 Vote: I do not like it

              In your comment "I had to read twice to see whether zero rotations would be allowed, but was able to conclude from the problem statement that it was not. The announcement was not necessary." This portion is about problem C.

              And "And in my opinion proper reading is part of the challenge." this portion is universal as it is your opinion. Generally opinions are global unless you write them in problem C(cube) scope { }.

              So again erroneous statement...

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6 years ago, # |
  Vote: I like it +19 Vote: I do not like it

Enough "IMPLEMENT" dose today, time to sleep.

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6 years ago, # |
  Vote: I like it +3 Vote: I do not like it

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6 years ago, # |
  Vote: I like it +2 Vote: I do not like it

worst c i ve ever seen so far in my life

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can someone plz tell me why am i getting error in problem C in pretest 7. Here is the code http://ide.geeksforgeeks.org/gZt7f3 Thanks in advance

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    6 years ago, # ^ |
    ← Rev. 3   Vote: I like it 0 Vote: I do not like it

    Your solutions fails for test case: 1 1 6 6 2 2 2 2 4 4 5 5 6 5 6 5 1 4 1 4 3 3 3 3 Your output : NO correct output : YES

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      You miss something, this test case is not valid. Because problem says, "There are exactly 4 occurrences of all colors in this sequence."

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    If I correctly understand what you do: A) There are two more sequences for "temp": 3 4 17 19 10 9 16 14 and 1 2 18 20 12 11 15 13. B) Your sequences in "temp" are disordered: for example, the first shoud be 1 3 5 7 9 11 24 22. C) You fill "t" wrong: you should move 7 to 1, 6 to 0, and so on.

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      yeah that 7 to 1 and 6 to 0 is taken care in that for loop. And yeah i ve missed those two sequences. Thanks.

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6 years ago, # |
  Vote: I like it +305 Vote: I do not like it

Relevant Meme for Problem C?

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6 years ago, # |
  Vote: I like it +136 Vote: I do not like it

I want to explain situation with today's round.

Yes, it's unrated and I appologise for it and will try my best to make this never happen again. Despite it, hope you liked the problems.

Problem preparation is a very hard process and it's quite easy to make a mistake there. Hopefully, Polygon platform was designed and it helps to find most of errors automaticly. Moreover, before any Codeforces round some people solves it before beginning to make sure that everything is all right. In most cases it's enough to make sure that there are no mistakes there, but today it wasn't enough. Error in stament of problem D today was done during rewriting statemnts from drafts, which happened too late, so most of the testers read correct draft of statement, but not the final version with mistake. Of course, many people read final version of statement before beginning, but nobody noticed that something changed between these two versions.

Of course it was a good lesson, and I will try to be much more careful next time.

Sorry again.

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    6 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    By the way, did you see the problem C? What do you think about it?

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    While posting the editorial, I will REALLY appreciate if you guys can help us grasp an elegant way to do problem C (rubick's cube) for this round. My code was all mess (and failed pretest 7 XD) and it boiled down to me not able to implement it elegantly. I will be grateful if that can be considered! Thanks :)

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      my code get accepted in the pretest but i think it will fail in the system testing . anyway my approach is to check if there is only two sides facing each other have the same color .

      for example if we look at the sample test the side 0 is facing , 3 is facing 4 and 5 is facing 1 .

      if all numbers in 1 are equal ,all numbers in 5 are equal and there is no other side whose numbers are equal then the answer is yes otherwise the answer is no . sorry for my bad englsih .

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      6 years ago, # ^ |
        Vote: I like it +17 Vote: I do not like it

      You only need to implement only 3 moves to perform all required moves. See my comment below in this blog post. Code: http://codeforces.com/contest/887/submission/32027887

      Btw, its Rubik's Cube! ;)

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    6 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    If author had added the model pictures in problem statement, maybe the testers would have been more enthusiastic and there would be no issues in problem D

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    No worries, we understand that mistakes happen. I'm sure you'll proofread everything very carefully in any round from now on!

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6 years ago, # |
  Vote: I like it +1 Vote: I do not like it

I like the problems, but I can't see how they were tested by 6 people. Or you mean each of them tested one problem?

Also I think changing the author's solution for D to match the problem statement would've been a better decision.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

WA on pretest 6 on F anyone ?

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

"if the left model from this pair is higher than the right model from this pair."

RIP 2 hours of my life used in solving a wrong version of the problem.

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6 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Any insight for Problem F, please?

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it +5 Vote: I do not like it

    Here is my idea that I think is right but couldn't implement correctly during contest:

    Lets start by compressing the heights of the models. Then go over each model and find the first and second models to the right of him(I will call them nxt[1] and nxt[2]) that are shorter than him ( you can do this with segment tree). After we do this lets call every model i whose (next[1] — i) > k "bad". Now its clear we must do a swap with a left model that is atmost K models to the right of every "bad" model. After that, I give every model a lower bound and an upper bound of the height of the model he will be swapped with:

    lower bound — min(a[i+1],a[i+2] ..... a[i+k])

    upper bound — min( every model that has model i as his nxt[1] and nxt[2] — that model is > k)

    After having both of these things. I go over every potential left model and find if there is intersection between him and some lower and upper bound. If there is, the answer is yes otherwise its no

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      6 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      Can you explain what you mean by "that model is > k" in your line explaining the upper bound? Thanks.

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        6 years ago, # ^ |
          Vote: I like it +5 Vote: I do not like it

        Yes. I'm sorry for wording it badly (Don't know how to use LaTeX).

        nxt[i][2] is the second index to the right of the model i that is shorter than him, right?

        since we are swapping the nxt[i][1] of that model with someone else, we must rely on nxt[i][2] now. If the distance between i and nxt[i][2] is more than k we must rely on the model we are swapping nxt[i][1] with, and giving it an upper bound( since the model we swap it with will have to be shorter than all models that will rely on him)

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          6 years ago, # ^ |
          ← Rev. 2   Vote: I like it +3 Vote: I do not like it

          How did you solve WA on test 6? I can't seem to figure it out unfortunately, and I can't understand your code.

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            6 years ago, # ^ |
              Vote: I like it +5 Vote: I do not like it

            My WA was that I forgot when we swap the left model must be taller than the right one. And also sorry for the messy code, too much pressure in the last 15 minutes :D. If you have questions regarding the code feel free to message me.

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    My understanding of task was wrong. Don't waste your time on text below.

    My idea (http://codeforces.com/contest/887/submission/32033565) got WA at 12 pretest.

    A) Make array Values[n]: models and designer (zero value).

    B) Make min segment tree using Values.

    C) Get last position L in [0; n — 1] where Values[L] <= MinFromTree[L + 1; min(L + k, n)]. It means that model L is not taller than all of k next models.

    D) Check (L + k + 1) position — position of (k + 1) model after L model:

    D.1) (L + k + 1) < n // Don't touch designer.

    D.2) Values[L] > Values[L + k + 1] // Reasonable swap.

    D.3) Values[L + k] > Values[L + k + 1] // Allowed swap.

    E) If all D conditions are true, swap (L + k) and (L + k + 1) in Values and tree.

    F) The same as step C.

    G) If L is undefined, print "YES".

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    6 years ago, # ^ |
    ← Rev. 3   Vote: I like it +10 Vote: I do not like it

    My short description:

    A — the leftmost position of model who violates the beauty (a lower model is more than k positions to the right).

    We must swap the higher model with lower on position A+k — I think I am able to sort of justify/prove that — if it is not possible, NO.

    Look for the biggest value lower than a[A] to the right and take the leftmost such value — I can't prove/justify that so it might be wrong. Just wrote couple of examples which showed that it was working and could not find a counterexample — call this pos.

    If there is no pos -> NO.

    Swap a[A+k] with a[pos] and verify that everything looks good -> YES or NO.

    Verification could be easily done with segment tree.

    Could somebody please provide a counterexample or some justification of the above solution? It was accepted: http://codeforces.com/contest/887/submission/32033530

    Thanks!

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6 years ago, # |
  Vote: I like it +28 Vote: I do not like it

I've never been to Div. 1. I have tried, I have come close, but I couldn't. And then today, I performed well at last. Well, maybe the hacks were the main boost today, but still, it's a part of CF, right? And I was happy that at last today I'll be in Div. 1. And then, it was unrated. I know many of you have faced this, but still, it hurts...a lot!!! I just don't know what to say. Guys, before arranging a round, please be careful :( I don't know if I should be angry or sad or frustrated. I know you guys will say, "you will get more chances" and all, and "if you are a good coder then this shouldn't bother you, you'll (should) be in Div. 1 without this", but still, it's painful AF!

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6 years ago, # |
  Vote: I like it +238 Vote: I do not like it

When you take this much pain to visualize problem C and the contest is unrated -_- :p

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6 years ago, # |
  Vote: I like it +8 Vote: I do not like it

32026568 Check out this AC code for Problem C today.

If checking for all rotation was the solution , Then this was the worst Problem C ever !

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6 years ago, # |
  Vote: I like it +52 Vote: I do not like it

Dear codeforces, you now really need to make a contest this weekend for us to forget about what happened =)

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I lost 15 minutes because first image is wrong in problem C... And that's time to hack and think... :)) :))

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6 years ago, # |
  Vote: I like it +2 Vote: I do not like it

This is really disappointing.

I mean , first you have rounds in such an irregular fashion (sometimes 2-3 contests in 2-3 days and sometimes 1 in 7-10 days) and then it gets unrated.

Surely programming is more about learning new things and contests are a great source for it but what is the point of trying a problem when its not even correct.

I believe admins should take care of this now more seriously.

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6 years ago, # |
  Vote: I like it +4 Vote: I do not like it

Oh my goodness.Not a nice round,right?

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Shiram to contestteon

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6 years ago, # |
  Vote: I like it -11 Vote: I do not like it

Please make the contest rated. This was my best performance ever. Please :'(

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6 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I think it was the worst round of all what I saw. All what I can do after I has been solving problem C is never to go to the Codeforces, I'm sorry authors.

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Well problems E and F were nice. I didn't look at A, B, C and D but the last two problems were much better than in a lot of div.2 rounds — in a lot of div.2 rounds last 1/2 problems are just obvious. In this round the last two problems didn't have an obvious solution at all. So it's wrong judging a round by just the first couple of problems. IMO the contest was nice and I don't see why the round is hated so much.

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      6 years ago, # ^ |
        Vote: I like it +35 Vote: I do not like it

      E is just dirty Geometry.

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      6 years ago, # ^ |
      ← Rev. 3   Vote: I like it +25 Vote: I do not like it

      It's the very strange position. Why do you forget that this round is definetely not for you? What can do a usual Codeforces Div2 member? Do you really think that they won't hate it, when they had the E and F problems which they knowingly couldn't solve just because they hadn't skill like you, the D problem which was wrong and the C problem which supposed a stupid realization? And what can I say to my pupils? When I will say: "You need to solve Codeforces contests because it's very beneficial for your skill", how will they believe me when they spent 2,5 hours of their time senselessly and they were deprived pleasure?

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        6 years ago, # ^ |
          Vote: I like it +5 Vote: I do not like it

        Agree. I have just started Codeforces and I was really scared yesterday.

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6 years ago, # |
  Vote: I like it +6 Vote: I do not like it

That moment when you open up someone's code to hack, but instead find out locking yours' one was a big mistake :') The round being unrated came as a blessing.

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6 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Problem C was irritating. But for an idea you can notice following:

  1. Moving right face anti-clockwise is equivalent to moving right face clockwise thrice.
  2. Moving right face clockwise is equivalent to moving left face anti-clockwise.

So you only need to implement 3 moves!

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You can only solve the Rubik doing one rotation if and only if there are exactly two sides already solved, and they are opposite to each other.

    With that in mind, there are only 3 possible moves.

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      6 years ago, # ^ |
      ← Rev. 4   Vote: I like it 0 Vote: I do not like it

      Yeah, but in this case you have to make cases on which moves to do, but from what I told, you can implement all the moves using three moves without digging up the cases!

      Btw its not Rubik, he was the person who invented it, its 2x2 Rubik's cube or Pocket Cube! ;)

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    6 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Plus there were some test cases in which the configuration of solvable cube was not possible Test case 46- 1 1 1 1 2 2 3 3 6 6 6 6 5 5 4 4 3 3 2 2 4 4 5 5 :/

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6 years ago, # |
  Vote: I like it +4 Vote: I do not like it

After seeing C , I really beleive YellowDreams . I was like trying to find some pattern but on seeing other solution,I know It was sh*t :(

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6 years ago, # |
  Vote: I like it -18 Vote: I do not like it

"It was at this contest Denisson knew he fucked up." -Morgan Freeman (Red), The Shawshank Redemption

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6 years ago, # |
  Vote: I like it +7 Vote: I do not like it

The author got a glimpse into the future, when he set the title for problem D: "Ratings and Reality Shows". An adjusted rewording could be "Reality Shows the Ratings are unaffected".

Unfortunately, nobody noticed the forewarning in the title.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can 3 digit number be formed in B problem?

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it +2 Vote: I do not like it

    No you can't

    You need a minimum of 19 digits to form 99, one zero and two of each other digits

    Sample test 2 has the largest answer

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Yes, taking one number from each 3 dices

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6 years ago, # |
  Vote: I like it -13 Vote: I do not like it

Starting from this contest, I hate Rubik's Cube.

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6 years ago, # |
  Vote: I like it +6 Vote: I do not like it

"it using one rotation" It should be "it using exactly one rotation" and highlight.

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6 years ago, # |
  Vote: I like it +7 Vote: I do not like it

The goal of the contest should be 'improving problem solving skills' and not just 'improving ratings'. Problem setters must have cross checked all the problem properly because this type of things disappoint a lot, but they are also human and they are allowed to make mistakes.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

OH! I just notice problem C ask for one rotation And I have written a web pages can show multiple rotating approach.

Debugging for a long time, wanna cry, thx for unrated.

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6 years ago, # |
  Vote: I like it +13 Vote: I do not like it

The best solution for Rubik's Cube I've found so far: 32027198

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What is the case for B where most solutions would fail? I got a WA on test 49!

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    The solution for B which got a WA on test 49, that's because you use more than one digits in one cube to build a number. :)

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

http://codeforces.com/contest/887/submission/32028326 It is my solution for problem C and it isn't so hard, I think.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

good

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can someone tell me why am i getting Runtime error in problem A on pretest 4. Here is the code

http://coliru.stacked-crooked.com/a/5676d8eb514b7ae4

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    6 years ago, # ^ |
    ← Rev. 4   Vote: I like it +1 Vote: I do not like it

    stoi converts string to an int value,so "11111111111111111111111111111111111" falls out of the range

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      any hint to fix it ?

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        6 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        Operate on string or char array itself . Don't use int/long/long long variable to store the binary number .

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6 years ago, # |
← Rev. 2   Vote: I like it +18 Vote: I do not like it

Prob C is shitty, and one of the most important info is not there, at least before I asked them at 1:30

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6 years ago, # |
  Vote: I like it +26 Vote: I do not like it

I really don't understand how the Codeforces Testing system works? Despite having so many testers, why are there such critical flaws in the problem statements?

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    Statements has changed after testing, that's why nobody noticed mistakes in statements. Of course, changing statements after testing is a bad idea. I hope this situation will never happen again, at least until the coordinator of rounds changes.

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6 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Waiting for editorial of Problem C.

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6 years ago, # |
← Rev. 4   Vote: I like it +3 Vote: I do not like it

wup wup that's the sound of the police Just same code... MatheusLealV -> 32033737 UmCaraLegal -> 32033714

EDIT: Ahh, contest isn't rated. Nevermind.

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Rated or not, cheating is always forbidden!

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      6 years ago, # ^ |
        Vote: I like it +27 Vote: I do not like it

      Cheating at an unrated contest, facepalm

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it -8 Vote: I do not like it

    I just noticed that they cheated on problem F. It means that I'm the only person to solve F during contest legally :P

    vintage_Vlad_Makeev

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I saw quite a few requests to get another contest quite soon, to make up for this one. I think that you will not get the next contest too soon if you are down-voting contest authors' so badly.

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6 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Basically me in this morning

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can someone explain why something like that would happen ?

I tested the example on codeblocks and my answers were right but im getting wrong answer on problem b my output is not 0.. you can try it on your compiler

http://codeforces.com/contest/887/submission/32035119

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    6 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    Just initialize s and t. And you don't have to check 0, start from 1.

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      6 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it

      thx there are several not necessary things or mistakes in my code but i was asking why it's different output

      when i run this example

      3

      0 1 2 3 4 5

      6 7 8 9 0 1

      2 3 4 5 6 7

      i get 87 on my compiler but the judgement protocol gives 0 to my output you can try it on codeblocks it won't give 0

      maybe they have something wrong with their judgment

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        6 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Your code gives 0 in "Custom invocation". As neckbotov said, you should initialize s and t (with zero).

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          6 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          man I hate these stupid mistakes.. there is no need for t too 98 is the highest possible number

          I fixed it thx for help

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

It is too much, man

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

unrated! really? -_-

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6 years ago, # |
  Vote: I like it +32 Vote: I do not like it

Denisson needed only 1 blog to become the worst contributor :(

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6 years ago, # |
  Vote: I like it +2 Vote: I do not like it

CF predictor was showing +7...I could have bacome a pupil after 8 months of Newbie life...."Sigh" Why so cruel

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6 years ago, # |
  Vote: I like it +11 Vote: I do not like it

I know most of you guys are disappointed in this round. But lets just appreciate the problemsetter cuz it is not an easy thing to make a round

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

In problem C some of the test cases are wrong because the 2X2X2 Rubik's cube will be in unsolvable state Test case 46- 1 1 1 1 2 2 3 3 6 6 6 6 5 5 4 4 3 3 2 2 4 4 5 5 this configuration of cube is not possible

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

76 people got AC on problem D. Did they get it on correct solution or wrong solution?

Should I submit D? Is it fixed now?

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6 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Too Terrible.

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6 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Can anyone explain the solution for D? (The real D, not the D in the problem statement)

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6 years ago, # |
← Rev. 2   Vote: I like it +85 Vote: I do not like it

ENG: What is wrong with everyone? Everyone is mistaken. I think the one unrated contest isn't reason to hate author. We learn from mistakes and must support him. Actually, problems were good. One more educational round...
RUS: Что со всеми не так? Ошибки делает каждый. Я не думаю, что один нерейтинговый контест настолько большой грех, чтобы ненавидеть автора. Мы должны поддержать его. А ведь, задачи были действительно хороши. Еще один поучительный раунд...

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    6 years ago, # ^ |
      Vote: I like it +28 Vote: I do not like it

    I agree, -483 is too harsh. It's not the first unrated contest and won't be the last. I'm sure he tried his best to make it work...

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      6 years ago, # ^ |
        Vote: I like it +14 Vote: I do not like it

      Btw I can't agree that Denisson 's one is more notorious than nssprogrammer 's one. (-688 votes on comment < -483 votes on blog). This is his first contest on codeforces, and actually plagiarism is one of the worst thing in the prograamming contest.

      This is not plagiarism, or not the worst thing (Half of problems are not bad), so I think the weight of indiscretion is not larger than nssprogrammer 's "Notorious Coincidence".

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    6 years ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    Here the problem is not whether contest is rated or not,but what matters is time.here most of people who are participating after leaving some important work e.g. that time which I should be devoting to prepare for exams, sacrificing the midnight sleep, some may be having a very tight schedule after job, and they are doing contests instead of relaxing and spending time with family. In such a scenario, It definitely hurts if u have to spend 2hrs unproductively.

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      6 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      But it means you should care about risk of this. If I encountered in the same pattern I would think that "it's unrated, but it's just a coincidence. I should think about the possiblilty of unrated (note that it doesn't mean I will ask whether the contest is rated or not)". That's one of what programming contest stand for, I think.

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        6 years ago, # ^ |
        ← Rev. 2   Vote: I like it +10 Vote: I do not like it

        Sure, it's always a risk whenever you do anything. But if there's a bad contest of course people will downvote for the wasted time.

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6 years ago, # |
  Vote: I like it +12 Vote: I do not like it

When will the editorial be published?

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6 years ago, # |
← Rev. 2   Vote: I like it -50 Vote: I do not like it

Denisson I'm getting WA on test 37 in D. Is it my bug, or is the problem still not fixed?

I was just being really really careless.

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6 years ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

How To Solve Problem B?

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6 years ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

Can Someone Explain Problem A Div 2

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    6 years ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    First of all, 64 = 1 000 000 We need to find position of the first '1' at the string, then just calculate the count of zeros between pos and length of string. If we can make 1 000 000, then the answer is "yes"

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

When is the editorial posted?

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Wow, I noticed that the problem A, C, D (problem which the factor of downvotes) was made by .tx, not Denisson, by seeing editorial. I think his responsibility is light and should not get too much downvotes.

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    6 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    I really don't think that the fault rely in only one person, please stop point fingers.

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6 years ago, # |
  Vote: I like it -8 Vote: I do not like it

I really enjoyed problem C. I would like more such problems in contests. But most people dislike C.

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6 years ago, # |
  Vote: I like it +23 Vote: I do not like it

It is Codeforces Round #444, the 4th problem went wrong, and now this post has 444 downvotes!

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

it's unrated , i am a little uncomfortable.

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6 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Denisson just turned things up..From -102 to +18...

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6 years ago, # |
  Vote: I like it -11 Vote: I do not like it

What was this contest? How could have anyone allowed the setter to propose these problems?

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6 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Why a lot of minuses? Because it isn't rated ?! If it will be rated, you will say "It's unfair". Or because system was bad. Can you make system like it, if no, respect other people's work!

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5 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I found it not the contest blog with the most downvotes. For Codeforces Round #571 (Div.2) has surpassed this!

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