physics0523's blog

Codeforces Round #654 (Div. 2)
By physics0523, history, 5 years ago, In English

Codeforcesの皆さん、こんにちは!(Hello, Codeforces!)

I'm glad to invite you to my first contest, Codeforces Round 654 (Div. 2) which will be held on Jul/01/2020 16:35 (Moscow time) (notice earlier time than usual). All of the problems were mainly written and prepared by me. The round is rated if your rating is strictly less than 2100.

You will be given 6 problems (one problem has a subtask) and 2 hours to solve them. Please, read all the problems.

I would really like to thank:

The scoring distribution will be announced later.

Good luck, have fun and wish your high ratings :)

UPD: Scoring distribution : $$$500 - 1000 - 1250 - 1500 - (1500 + 1250) - 3000$$$

UPD: Editorial is out

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

Comments Comments (411)
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5 years ago, # |
  Vote: I like it +2 Vote: I do not like it

Auto comment: topic has been updated by physics0523 (previous revision, new revision, compare).

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

Thanks for all of these frequent rounds!

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5 years ago, # |
  Vote: I like it +137 Vote: I do not like it

I hate Physics. Hopefully no problem related to physics!

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

    Even though I love Physics , I still hope there will be no physics related problems. XD.

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

    same here pal.XD

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

    I think Physics problems would be easier than the problems in this round

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

Good luck on your maiden round!

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5 years ago, # |
  Vote: I like it +61 Vote: I do not like it

As a tester, I can say that the problems are really interesting and hopefully you will enjoy solving them :)

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    5 years ago, # ^ |
      Vote: I like it -273 Vote: I do not like it

    I dont know why testers are commenting a lot just for upvotes!? The only thing you done is you participated in a contest few days before most of the people and i dont see anything special to upvote u!

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      5 years ago, # ^ |
        Vote: I like it +569 Vote: I do not like it

      The only thing you done is you participated in a contest few days before most of the people and i dont see anything special to upvote

      Nah this isn't the only special thing about testers.
      He also left one rated contest so that others can enjoy one round.

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      5 years ago, # ^ |
      ← Rev. 3   Vote: I like it +251 Vote: I do not like it

      Down voted, it's not true about many testers, you can't even understand how hard being a good tester is.

      P.S. I feel personally attacked. =(

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        5 years ago, # ^ |
          Vote: I like it -285 Vote: I do not like it

        Oh my god! Ok i upvoted you becuase its the only thing you want :( and its you third time you are editing your comment to dont get downvote!

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          5 years ago, # ^ |
          ← Rev. 2   Vote: I like it +240 Vote: I do not like it

          What is wrong with you, I want you to understand how important testers are, some of testers duties are :

          1. They should try submitting heuristics/wrong solutions, to make sure tests are strong enough.

          2. They should help problem setters to replace the problems if needed.

          3. They should write many different solutions for a single problem(if needed), to make sure unintended solutions that are wrong or are slow wont pass.

          4. Doing many other things to make sure tests are strong, problems are not spoiled, statements are clear, pretests are fine and etc.

          I saw that your comment has many upvotes, so it probably means many people don't know about testers, so I wrote this to show you how being a good tester is , not for upvotes.

          P.S. I enjoy editing my comments, you cant blame me for that.

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            5 years ago, # ^ |
              Vote: I like it -259 Vote: I do not like it

            Upvoted as i said

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            5 years ago, # ^ |
            ← Rev. 2   Vote: I like it +45 Vote: I do not like it

            Agreed. A good contest is the result of hardwork and collaboration of all testers, problem setters and coordinators.

            I would like to thank all of you for making so many good contests for us.

            Hope to have fun in this contest too:)

            All the best to all!

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      5 years ago, # ^ |
        Vote: I like it +229 Vote: I do not like it

      As a tester, I can confirm that we do absolutely nothing in a grand conspiracy to gain contribution points by making meaningless confirmations on the contest announcement.

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

        As a non-tester who would very much like to become one, how can I get in on this conspiracy?

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

          Just pretend you're a tester in the comment section, then they'll add you to the tester list in the announcement.

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        5 years ago, # ^ |
          Vote: I like it +20 Vote: I do not like it

        I love it when people compose formal responses to jokes.

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    5 years ago, # ^ |
      Vote: I like it +33 Vote: I do not like it

    this is what all testers say about their rounds:))

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

      Wait for the next Global round. :)
      For spoilers about tester comments of next Global join AC.

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    5 years ago, # ^ |
      Vote: I like it +107 Vote: I do not like it

    Scam

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    5 years ago, # ^ |
      Vote: I like it +50 Vote: I do not like it

    Proof of a conspiracy theory by testers to gain contribution.

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    5 years ago, # ^ |
      Vote: I like it +48 Vote: I do not like it

    Frequent comments like these is why nobody takes such comments seriously now!

    If you found the questions interesting, you are clearly lying and spamming for contribution. As simple as that.

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

      Or maybe they simply should be banned of the tester position as they have a much different taste for problems than the CodeForces community does.

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

    Did some comments disappear? I think I saw few other replies to this comment yesterday.

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

      Yes, nima_oof_che_mamehaii's reply disappeared, and all of the replies to it with it.

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

        Do you think this is intentional or some other bug in the Codeforces website?

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

          Probably intentional.

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

          Yes,It's intentional..After many negative vote some commment filter out.I think this feature added from past 2 contest ..I think it's a good initiative.

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

      Yes. They tried to silence me revealing the secrets about the tester-contribution conspiracy.

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        5 years ago, # ^ |
        ← Rev. 2   Vote: I like it +9 Vote: I do not like it

        Hi i forgot to reply your message when my comments was there. you replied me that you and lots of testers didnt do it! And im gonna say yes! I agree and i was saying some of them are doing it in every single contest and i was replied to tester i think that its not fair! I dont realy care about upvotes and downvites i just say something that i believe so im sory if any one get mad at me becuase if those comments but im saying that these kind of works are not cool :(

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

          some of them are doing it in every single contest

          I agree with that, but I'm not one of them, I joke about those things sometimes, but I really don't mind.

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    5 years ago, # ^ |
      Vote: I like it +58 Vote: I do not like it

    Codeforces should have option of downvoting comment even after upvoting it.

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      5 years ago, # ^ |
        Vote: I like it -14 Vote: I do not like it

      You can still downvote the comment next to that one.

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5 years ago, # |
  Vote: I like it +209 Vote: I do not like it

I was master when I tested the round, I wouldn't have done it if I knew I would have missed such a great round :((

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

What is the meaning of subtask? Does this mean a problem will have an easy and a hard version?

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5 years ago, # |
  Vote: I like it +64 Vote: I do not like it

Glad not seeing comment section filled with memes this time

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5 years ago, # |
← Rev. 5   Vote: I like it -57 Vote: I do not like it

Good luck everyone. This community is insane lol

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    5 years ago, # ^ |
      Vote: I like it +22 Vote: I do not like it

    Here I was wondering why there were so many negative feedbacks until I saw the revision history XD

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

      I just said I loved physics and people got offended, so had to change. I still don't know the reason

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

        Its not necessarily that people are offended. They might not agree with your opinion and hence the negative feedback.

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5 years ago, # |
  Vote: I like it +46 Vote: I do not like it

頑張って皆！Good luck everyone!

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

I love Japan and the Japanese so i'm excited for contest :D

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

    High possibility of involving anime characters

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5 years ago, # |
  Vote: I like it -42 Vote: I do not like it

Hope , we will see Geometry related problem.

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

Looking forward to this round!

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

Physics is evrywhere :v

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

My UI of codeforces has been shifted to left side and I'm unable to see users and search problems with specific rating, Is there anyone facing the same issue since morning?

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5 years ago, # |
  Vote: I like it -75 Vote: I do not like it

well all the testers can anyone just give slightest of hints as to what type of problemset is coming our way tommorrow

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    5 years ago, # ^ |
    ← Rev. 3   Vote: I like it +5 Vote: I do not like it

    What do you think their replies would be ...other than "Some Interesting Problems".

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      5 years ago, # ^ |
        Vote: I like it -62 Vote: I do not like it

      but still it would be much better if we get to know type of problems.maybe tiniest of clues

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

        "maybe tiniest of clues"

        Idk why.. but this sounds so-fuccin-funny..

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

    Sure. I was a tester. I can tell you. The problems are interesting. Have fun!

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    5 years ago, # ^ |
      Vote: I like it +20 Vote: I do not like it

    I'll give you a hint for the next 100 rounds, I know, even better. You'll see greedy, constructive, more greedy, elementary math, guesswork, and greedy. You only have a chance at an actual cs problem if you can make it to the last problem, otherwise you'll write 20 lines of code since people on a platform called "code"forces do not enjoy coding.

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

      Let me guess, F is your favourite problem in the contest?

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        5 years ago, # ^ |
        ← Rev. 2   Vote: I like it +7 Vote: I do not like it

        I'm too dumb to get to it. But I saw by your comment you thought it wasn't great ig :(

        But i'd rather code 30m for boring problem (though it is probably not boring for me) than not code at all. So probably.

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

      Highly disagree. There's a fair amount of regular coding at a regular software engineering job. There are tons of "put a twist on a standard CS algorithm"-type problems on Leetcode.

      This is the only place with such a high ratio of actual problem solving / lines of code. Let's keep it that way.

      This contest wasn't the best one, but not because the implementations happened to be short. There are plenty of other contests with problems with similarly short implementations but that were nonetheless elegant and delightful.

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

      I agree not many problems related to Binary Search, Graphs Algorithm etc. nowadays....

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5 years ago, # |
  Vote: I like it -22 Vote: I do not like it

is it unrated?

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    5 years ago, # ^ |
    ← Rev. 3   Vote: I like it +1 Vote: I do not like it

    It is rated if your rating is strictly less than 2100 !!

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

    The answer is both a yes and a no.

    (Did you read the announcement?)

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

Dude loves physics so much, he used it as his username, pretty sure some physics related questions,any ways good to have frequent rounds.

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

    And if tourist were the problem setter you would expect problems themed around sightseeing tours.

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5 years ago, # |
← Rev. 2   Vote: I like it +51 Vote: I do not like it

Add the scoring distribution. If you can solve all the problems in a moment, you'll achieve exactly 10000 pts!

Auto comment: topic has been updated by physics0523 (previous revision, new revision, compare).

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

All the best and hoping for a great round!!

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

Thank you for these frequent contests. we keep on learning and testing our skills it's really helpful

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5 years ago, # |
  Vote: I like it +33 Vote: I do not like it

Do we need to practice HC Verma or Irodov?

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    5 years ago, # ^ |
    ← Rev. 2   Vote: I like it -42 Vote: I do not like it

    This Comment is Deleted Due to negative feed back, don't know why but my comments are getting down votes all the time, even though the content of my comments are genuine & accurate. From now on I decide to never give any suggestion to anybody on codeforces in the form of comments , because I may not be intelligent enough to give suggestions to most of you.

    thanks!

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

      Dude, it is a pun on the problem setter username

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

I have participated in the writer's contests on another platform (Hackerrank), and his problems are always well-prepared and fun to solve.

I believe this round is going to be great as well!

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

    Do you have a link to his contest(s) there?

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

      Check This.. it's writer is physics0523 .

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

      Here is the link to his latest contest.
      Unfortunately problem statements are written only in Japanese, but the problems are like the ones from AtCoder Beginner Contest.

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

A contest a day keeps the pressure away.

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

what's the meaning of (1500 + 1250) in scoring distribution for 5th problem ? can't we just write 2750 instead? Thanks in advance !!!

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5 years ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

Hope these long queues will be solved as fast as possible. And we will have good contest.

And it is solved :) when i returned to submit the problem after writing comment, it was solved.

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

I'm a beginner in CP and became PUPIL in last DIV 3 contest solving 4 problems. Hoping to do well in this contest too. But the problem I'm facing is I'm able to solve A, B in div 2 but on C I always get stuck. So any suggestions how to cover this gap between B and C?

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

    I think the only thing you need , is "practice" .I also in your level & stuck on C.

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

      Yes, I am practicing a lot. And when I see solutions of C then most of the time I find a new concept which I don't know and then I try to learn that from youtube or from somewhere else.

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5 years ago, # |
  Vote: I like it +22 Vote: I do not like it

2 hours remaining to start the round. But wrong division cases on Codeforces Round 653 (Div. 3) is not fixed yet. Some experts get their rating changed. Will it be fixed before the round starts?

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

    Maybe they registered for div3 round before they became expert.So they were not out of competition.

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

      Yes i know that. But as far i know mike fixes it manually at the time of rating change.

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    5 years ago, # ^ |
      Vote: I like it -10 Vote: I do not like it

    Who cares?! ))

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

      Some expert may solve the round carelessly since the round is not rated for him. They might care about unwanted rating change.

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5 years ago, # |
  Vote: I like it -43 Vote: I do not like it

making the start 25m later would be perfect!

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

Hope the contest will be as interesting as the score distribution .

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

I hope in this round "in queue" will not be shown for longer time

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

how can someone become a tester .... i want to experience being a tester

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

Hlo Guys. I am new here. What is the meaning of score (1500 + 1250) of 5th question?

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

Hope to become green

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

I don't like this round at all...

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5 years ago, # |
  Vote: I like it +78 Vote: I do not like it

And why did Akari have to make the E1 problem difficult? She should have kept quiet. Damn these front bench kids!!

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5 years ago, # |
← Rev. 2   Vote: I like it +91 Vote: I do not like it

No offense to the round writers, but problem B needs to be proofread by a native or advanced English speaker.

Edit: To clarify, I think the problems are interesting as always, but the phrasing and typos make the problem difficult to read for someone not familiar with the idea of the problem.

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

    I was just going to say this. If there are going to be any rounds in English, it is best they are authored properly. FFS!!

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

    Russian statement wasn't great either.

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5 years ago, # |
  Vote: I like it +43 Vote: I do not like it

Good-bye my rating!

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5 years ago, # |
← Rev. 2   Vote: I like it -72 Vote: I do not like it

Very Bad round with 90% maths

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    5 years ago, # ^ |
      Vote: I like it +116 Vote: I do not like it

    If you call these problems math, show at least one round which isn't math

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      5 years ago, # ^ |
        Vote: I like it -22 Vote: I do not like it

      that's cause all cf rounds are too math based.

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    5 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    The first question was basic arithmetic, we can't complain. 2nd question required you to know sum of first n Natural numbers which was also not any tough maths. C was casework, D was pattern. Why are u complaining?

    (pls correct me if I'm wrong somewhere)

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5 years ago, # |
  Vote: I like it -37 Vote: I do not like it

Mathforces :(

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5 years ago, # |
← Rev. 2   Vote: I like it +57 Vote: I do not like it

It seems like I am the only one who liked the contest. ??? Feel free to downvote if you disliked it. IMHO it is a balanced contest and it is not that MathForces as some of you think.

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

    I don't feel like it's a mathforces round at all. For me it's just easy problems with many corner cases and very unlikeable implementation. In C 4 i got WAs and my AC code is just 7 if statements

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

    For me it felt like mathhomeworkforces. I did not have any programming problem, it was all logic and E some formular.

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

Interesting problems, but Im too bad for them(

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5 years ago, # |
  Vote: I like it +155 Vote: I do not like it

WTF is going on with this comment section? Round isn't over yet

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5 years ago, # |
  Vote: I like it -17 Vote: I do not like it

I hate this B why I can't solve it spent the whole time on it :(

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5 years ago, # |
← Rev. 2   Vote: I like it +54 Vote: I do not like it

I'm curious how the testers easily understood problem B and didn't they feel D is too easy for div2D??

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

this contest was difficult for me

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5 years ago, # |
← Rev. 2   Vote: I like it -36 Vote: I do not like it

[Deleted]

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    5 years ago, # ^ |
      Vote: I like it +183 Vote: I do not like it

    Why, so that every time someone has a bad performance they can make the round unrated by uploading solutions?

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

      No. That guy was livestreaming his solutions on youtube (from start ). But I'm honest and didn't visit the site and solved what i could myself.

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

        I'm not saying that's what happened here. But I am saying that if you make a round unrated if there are cheaters, then every round will be unrated.

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    5 years ago, # ^ |
      Vote: I like it +47 Vote: I do not like it

    It was travisscott as it can be seen at 26:48.

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

    That's why number of LOSERS solving problem E increased exponentially suddenly at a certain point of time!!

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

      CF predictor shows -2 rating for me, damn if cheating happened like that, I'm happy with this rating xD

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      5 years ago, # ^ |
      ← Rev. 2   Vote: I like it +16 Vote: I do not like it

      In the video, only A, B and C were solved (and there were also two failed submissions on D).

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

    Due to actions of some of these people whole community suffers.Something should be done against them so that this is not repeated.

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

What is the pretest 2 for D?

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

ObservationForces

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

ConstructiveForces

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5 years ago, # |
  Vote: I like it +108 Vote: I do not like it

Did I accidentally open Codechef today for the contest?

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

    how would we know also are you blind?

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      5 years ago, # ^ |
        Vote: I like it +36 Vote: I do not like it

      Codeforces Rule #343: Ignore comments from unrated accounts

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        5 years ago, # ^ |
          Vote: I like it +43 Vote: I do not like it

        Codeforces Rule #434: Ignore comments from Master accounts registered 2 months ago

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

        Irony is you are the one breaking that rule

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

I feel bad for the problem writers because of the people who posted the solution to the contest on youtube.

On an unrelated note: is the contest going to be unrated?

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

    Plagiarism is checked I guess. So all those who copied will be anyway disqualified

    Please look into it MikeMirzayanov physics0523

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

      Even then, you still could've gotten the gist of the solution of the problem and simply rewrote the code with your own style. It's also extremely difficult (basically impossible) to check for plagiarism if you submit with another language.

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

        Especially the first 3 problems were just math formulas which are very hard to be checked for plagiarism.

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      5 years ago, # ^ |
        Vote: I like it +57 Vote: I do not like it

      We found the cheater, too. If some users copied some solutions, the plagiarism checker will work.

      I think the contest will be still rated because sadly there are always some cheaters.

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

        Even He cheated with youtube live.But got +543 ..Cheating is easy now :v And my some friend copy and change some variable , not caught by checker ! Is plagiarism jokes ?

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

      Don't count on that. it's very easy to beat Plagiarism testing of codeforces.

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

I don't know if this was intended or not, but I literally solved problem B using the samples without thinking in the main problem.

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

    I did that for A. :) Sample test cases clearly showed (n+1)/2 if one notices carefully.

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

Nice contest, easy D. I got pretest 9 failed for problem E1 anyone has a clue about that pretest

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

How to solve D? Greed- fill diagonally then it's left and right diagonal and so on...is giving wrong

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

    the idea is ok but when you reach the cell (n-1,n) have to finish with the cell(1,n) and so on (apply modulo when you reach n)

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

    Try 1 3 6

    Your code will return 4 110 111 011

    while it should return as mentioned: 0 110 011 101

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

Was C really just casework? (that's how I did it but..). I hate such questions, wastes time, and morale. Couldn't solve D due to it :(

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    5 years ago, # ^ |
      Vote: I like it +25 Vote: I do not like it

    My observation was that it's always optimal to put all the type 2 people first. The reasoning is that since they always take from the smaller pile, then the size of the pile they'll take from will be $$$x, x-1, x-2, ...$$$ (if $$$x$$$ is the original size of the smaller pile). The larger pile will never be taken by the type 2 people until its size is less than or equal to the size of the smaller pile, resulting the continuation of the sequence. Hence it's never better to put type 1 people first.

    The yes condition ends up being a+b >= n+m && min(a, b) >= m.

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

      That's it? 1 line of code. I tried caseworking and failed miserably.

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

        same here wasted lot of time

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

I solved B completely based on the sample cases. I have no idea what does the problem say! I just make it work on samples, I do not know if I am gonna pass system tests or not.

anyways, thanks for the round authors and testers.

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

can someone tell me why my E1 solution fails at pretest 9 ?

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

How to solve E1 ? Can someone point me my mistakes ?

int n, k;
vector<int> a; /// size n || sorted
bool solve(int x)
{
    int res = 1;
    for (int i = 0, p = 0; i < n; ++i, ++x)
    {
        while (p + 1 < n && a[p + 1] <= x) p++;
        res = (1LL * res * (p - i + 1)) % k;
        if (res == 0) return false;
    }

    return true;
}
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    5 years ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    I think your mistake is in these lines

    for (int x = max(k, mx + 1); x <= n; ++x)
        res.push_back(x);

    You only need to iterate to mx. That's enough. So basically erase these lines

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

      Yes, removing it give me AC, how stupid I was. Thansk for pointing out my mistakes

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

In problem B, The picture in sample test case changed during the contest. Initially there were only 3 green ticks. At the end of the contest, there were 6. This created confusion.

Proof-

During contest-Link

When I saw after the contest-Link

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

    Yes. The green ticks confused me (no matter how many they had). The clearest representation would be to group the pictures into 4 categories to show which ones are the same.

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

Back to specialist, RIP rating -100 :(

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5 years ago, # |
  Vote: I like it +39 Vote: I do not like it

Understanding problem B's statement alone should be rewarded with +50 rating

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

    gimme that rating, I understood the problem in one go. (cuz i read it too slow)

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5 years ago, # |
  Vote: I like it +33 Vote: I do not like it

I usually don't comment on the quality of rounds, but I think this round was really bad. A — C are just formulas and cases, and D is constructive. You literally could know zero algoritms, even not know binsearch and sorting, and still solve A — D, and this is really bad in my opinion.

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

First time I solved 4th, Thanks physics0523, you also gave the overflow details in testcase, thanks for that too, Last time I wasn't able to solve due to overflow.

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

I used floor((n-1)/2) + 1 as my answer but this failed on pretest 3. I wonder why? Even in the editorial, same solution is mentioned. I give (n-1)/2 + 1 it passes. Where is the mistake?

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

    return type of floor is a double type. So if the returned value is large it will be printed in scientific notation (like 5e+008). where as when you do (n-1)/2 the result will remain an integer type and all its digits will be printed as normal integer.

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5 years ago, # |
  Vote: I like it +252 Vote: I do not like it

F: Think for 0.2 seconds and implement for 30 minutes. What an amazing problem.

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

Weird template but ok

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

rip

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5 years ago, # |
  Vote: I like it +31 Vote: I do not like it

Most Ad-hoc round I have ever given on CF.

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5 years ago, # |
  Vote: I like it +116 Vote: I do not like it

Problem B was written terribly and also sample explantions were really bad. I won't say that the round should be unrated but it was one of the worst rounds by far in terms of problem statements.

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

    Misunderstood the problem and wasted a lot of time. RIP rating

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

      RIP English first... The diagrams were so confusing I just guessed formulas and hoped to get one that works.

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

    Totally agree. Things were terribly written in the problem B. Was the problem B made to check English and patience of people? One-liner formula was the answer after reading the worst problem statement.

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

    Exactly. What the hell did the green ticks mean ? He could have simply showed the correct 4 out of 6 in green ticks if at all that's what the author wanted to show. I was scratching my head for 10 min over that.

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

      yeah, ticks just messed up the statement further

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5 years ago, # |
  Vote: I like it +51 Vote: I do not like it

Boring contest

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

I hope that someone will have a good proof that why it was optimal to start with type 2 People in Problem C ! I am not able to reason it out! why Starting with Type 1 people is not optimal !

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

    My logic was that you can shove your unwanted cookies at type 1 at the end, and they'll eat anything.

    So, you should give your rarer cookies to type 2 people first

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    5 years ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    Its because type 1 people always chooses the cookie which is left MORE so they will never get angry if a cookie is left no matter v or c. Type 2 people choose the cookie which is left LESS so they will get angry if the cookie which is left less is finished. Attaching my code for your reference https://mirror.codeforces.com/contest/1371/submission/85648596.

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

      i understand the idea ! But during the thought process I had in my mind that during all this If we feed all the TYPE 2 people first their will come a time where The ratio of cookies will reverse ! And That can happen quite some times during this procedure how to deal with it ?

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

        Type 2 people are sadists they will try to eat up the cookies which are already less. So the number of both the cookies should at least be equal to the no of type2 ppl. The ratio won't reverse as type 2 will go on consuming the less cookies making it lesser.

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

What was B? I didn't even go further after reading 4 lines. Highly unclear. Problems must be easy to understand but hard to solve. Seems this was reversed.

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

    .

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

      What cheating happened ?

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

        .

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          5 years ago, # ^ |
          ← Rev. 2   Vote: I like it +7 Vote: I do not like it

          Its a request to make the round unrated. Worst Problem statements, Lengthy, confusing Adhoc Problems, Round full of cheating. Though my rating is getting a +45, but I don't care, because the round was terrible.

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

    B was like 5 lines of code wrapped in a ambiguous and confusing problem statement.

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5 years ago, # |
← Rev. 2   Vote: I like it +9 Vote: I do not like it

For question E, I have a claim that the answers are consecutive if there exists any. Can I ask for a proof / disproof of this claim?

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

    Suppose that $$$x$$$ is the smallest positive number where f(x) is greater than 0 (In other words, $$$x$$$ is the smallest possible amount of candies you need to start with so you can beat all the opponents).

    Suppose that $$$y$$$ is the smallest positive number such that if you start with Y candies, then at some point of time, You'll be able to fight at least $$$p$$$ opponents and win.

    The answer lies between [x,y-1] inclusively.

    for any $$$z$$$ < $$$x$$$ has f(z) = 0, so divisible by p, so [0,X-1] is totally unacceptable answer

    anything greater than or equal to $$$y$$$ has f(z) = k * p, which is divisible by p , so [Y,infinity] is also unacceptable answer

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

      actually, imo proving $$$f(z) = kp$$$ for $$$z \geq y$$$ is not trivial

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

        But it's trivial to prove that $$$f(z) = kp$$$ for $$$z \ge 10^9$$$. Since, $$$f(z) = n!$$$ and given that $$$p \le n$$$, $$$f(z) \mod p = 0$$$

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

    let $$$g(i)$$$ be the number of possible choices of $$$P[i]$$$ ($$$1$$$-indexed) for some $$$x$$$
    you can prove that $$$g(i)$$$ is the same for any valid prefix $$$[1, i - 1]$$$ of $$$P$$$
    obviously the number of permutations is the product of all $$$g(i)$$$
    you know that $$$g(n) \leq 1$$$ (since only 1 integer remains), $$$g(i) \geq g(i - 1) - 1$$$ (because you can still choose all the indices that were valid for the position $$$i - 1$$$, except $$$P[i - 1]$$$)
    so the values assumed by $$$g$$$ are consecutive, and if an $$$i$$$ such that $$$g(i) \geq p$$$ exists, a $$$j$$$ such that $$$g(j) = p$$$ also exists
    an $$$x$$$ isn't valid if there is some $$$i$$$ such that either $$$g(i) = 0$$$ or $$$g(i) = p$$$
    let $$$l$$$ be the maximum $$$x$$$ such that a $$$g(i) = 0$$$ exists, for $$$x' < x$$$, $$$g(i) = 0$$$
    let $$$r$$$ be the minimum $$$x$$$ such that a $$$g(i) = p$$$ exists; for $$$x' > x$$$, $$$g(i) \geq p$$$, so there is some $$$j$$$ such that $$$g(j) = p$$$
    so the only valid answers are in the interval $$$[l, r - 1]$$$
    these values are all valid because $$$l$$$ is maximum and $$$r$$$ is minimum

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

    Proof by AC: 85713453 (find minimum value in easy O(N), binary search to find the max value that works, print every number in between).

    Will update with my "proof" later.

    Proof:

    • Claim: f(x) can be written as some factorial, lets call it X!, multiplied by some mumbers <=X.
    • You can see that this is true when you calculate $$$p_i$$$, the number of possible numbers to go in the $$$i$$$th spot, after you've determined the first $$$p_0$$$ to $$$p_{i-1}$$$. f(x) equals $$$p_0 \cdot p_1 \cdot \ldots \cdot p_{n-2} \cdot p_{n-1}$$$. $$$p_i$$$ is calclated by (the number of numbers in the array <= x+i) — i. $$$i$$$ increases by $$$1$$$ each iteration, and because that is the only way for $$$p_i$$$ to decrease, is impossible to decrease by more than $$$1$$$. There is $$$1$$$ possible number that can go in the last position because only $$$1$$$ number is left, so the $$$p_{n-1}$$$ must equal $$$1$$$.
    • Thus, say you found the position with the maximum number of possibilities had $$$X$$$ possibilities, f(x) = X! * {some numbers <= X} because all numbers between $$$1$$$ and $$$X$$$ inclusive must be represented in $$$p_0$$$ to $$$p_{n-1}$$$.
    • This is important because you can say that $$$f(x)$$$ is divisible by all primes $$$<= X$$$ and not divisible by any primes $$$> X$$$, where $$$X$$$ is the number of possibilities of the index with the most possibilities.
    • You can also show that the $$$X_a \le X_b$$$ for all $$$a < b$$$. This is because having a greater value of x in f(x) will never result in less possibilities for any position.
    • Thus, for all $$$f(a)$$$ and $$$f(b)$$$, where $$$a < b$$$, if $$$f(a)$$$ is divisible by $$$p$$$, then $$$f(b)$$$ must also be divisible by $$$p$$$. $$$X_a$$$ is $$$> p$$$, and since $$$X_b \ge X_a$$$, $$$X_b > p$$$ as well.
    • Starting from the minimum working $$$x$$$ (before of which $$$f(x)$$$ is all $$$0$$$), no value of $$$x$$$ after the first non-working $$$x$$$ can work, so the answer must be in the form of a continguous sequence of numbers.
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5 years ago, # |
  Vote: I like it +16 Vote: I do not like it

It is ironical that someone who has physics in his username loves math!!!

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5 years ago, # |
  Vote: I like it +57 Vote: I do not like it

physics0523 write code for problem F. then he write problem for his code

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

Terrible legends to problems, most of the time was spent on understanding the statesment((

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

A lot of Observational questions. If it hits , you could get AC in 5 mins, otherwise many kept scratching, like me.

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

    Accurately put. That's exactly how it was. Hit the idea or hit the right youtube link. XD

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

    I'm pretty bad at Observational questions. Is there any tag related to such problems? I want to solve them. Problem like problem C, I mean.

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

Worst contest ever :/

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5 years ago, # |
← Rev. 2   Vote: I like it -12 Vote: I do not like it

logic in Problem D is the same as this problem from recent div3 contest

https://mirror.codeforces.com/contest/1360/problem/G

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

Can someone explain to me the solution to A? I used n / 2 with ceil.

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

    ans = n / 2 + n % 2, because if n is odd, then we have 1 + (n — 1), 2 + (n — 2) ... n

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

      or simply just (n+1)/2 as languages round down during division.

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

    print each test-case output in newline.

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

    Use ceil(n*1.0/2) it will work

    In your case, you are using n/2 which will be treated as int and to make it float multiply it with 1.0

    if n=5 your answer will be ceil(5/2)=ceil(2)=2
    but it should be 3 as ceil(5*1.0/2)=ceil(2.5)=3

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

      n was declared as float. I used ceil(n/2.0).

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

        float can't accurately represent all numbers up to 10^9. Needs to be double or done via integer maths.

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

Question B was not clear. In the first sample test case,they should have clarified that the 4th and 5th picture are also same (they have different r thats why they should be different). Wasted more than 1 hour on it (I figured the formula in 2minutes) and could not touch C and D properly. Plz,clarify these things.Even on asking the jury ,it said only the last picture(for 1st sample test case) is not considered but actually the last 3 pictures were not considered in the answer.

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

I hope Editorial has some brilliant solution for F. Otherwise it is one of the worst problems I've seen in a while.

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

I guess it will be hard to believe the testers that comment "problems are very interesting" after this round:(

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

Very good round!

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

    I think that it is in a sarcastic way!

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5 years ago, # |
← Rev. 4   Vote: I like it +100 Vote: I do not like it

Some of the shortest code for A-C that I've seen...

A: (n+1)/2

B: r >= n ? (n*(n-1)/2 + 1) : (r*(r+1)/2)

C: (a+b < n+m || min(a, b) < m) ? "No" : "Yes"

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

    please can you explain the solution of B and C,

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      5 years ago, # ^ |
      ← Rev. 2   Vote: I like it +26 Vote: I do not like it

      B: When $$$n > k$$$, then there are $$$k$$$ different patterns, one starting at each different day of the week. When $$$n \le k$$$, you only have the straight line pattern. So for $$$r \ge n$$$, you get $$$1+2+...+(n-1) + 1$$$. For $$$r < n$$$ there will never be enough days in the week for a straight line, so it's $$$1+2+...+r$$$.

      C: The observation was that it's always optimal to put all the type 2 people first. The reasoning is that since they always take from the smaller pile, then the size of the pile they'll take from will be $$$x,x−1,x−2,...$$$ (if $$$x$$$ is the original size of the smaller pile). The larger pile will never be taken by the type 2 people until its size is less than or equal to the size of the smaller pile, resulting the continuation of the sequence. Type 1 people always take from the larger pile, so you'll only fail if you run out of cookies. Hence it's never better to put type 1 people first. You also need to check if there are enough total cookies for all the guests.

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

    Include D as well :XD

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

    B should be (r*(r+1)/2), isn't it? Typo?

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

Any idea what does TC4 in E1 looks like?

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5 years ago, # |
← Rev. 2   Vote: I like it +147 Vote: I do not like it

Problem B is absolute trash, super unclear, and boring.
Problem C isn't better. Author, can you tell me what the interesting idea or approach is behind this problem? As for me, it's just about understanding problem statements and implementing stupid case analysis.

You know, >75% of participants solve only A, B, and C. So for them it was a 100% shitty round.

P.S. please never invite AmShZ and DasAnuDasah as testers anymore, if they find this round "really interesting" and "such a great".

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

    Solved A in 3 mins from then till now I am unable to cracks B's statement If B & C problems are like that how would anyone solve any on Div 2

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5 years ago, # |
← Rev. 3   Vote: I like it +23 Vote: I do not like it

Even A,B,C Solution found on youtube after 1 hours+ . Link. Please notice .MikeMirzayanov ..Please find all the cheaters or and if not possible hope this contest will be unrated.I know to make a contest, authors made so hard work,, But It is unfair someone copy the solution and take positive rating before our eyes And someone go down for only cheaters and gain negative rating . .

**N.B: I was not submit any solution cause busy sometimes on the contest time.Now i feel good cause some problem statement was unclear too , specially B..the contest was worst overall.

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

    It's impossible to catch cheaters. The first three problems are a simple formula so you can rewrite it however you want. In addition, many people were confused by the problem statement for B. Many questions were asked with disappointing responses. The problems were of really low quality so many people who usually solved the first 3 questions couldn't even solve 2! This would cause the cheaters to get a lot of positive rating change which is clearly unfair to the community. Thus, I think that we should make this round unrated.

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

      Listen to the community: looking at the comments I can find only 2 which say that they enjoyed the contest (not including testers who apparently have a different taste of problems than we do). Clearly, the contest is disappointing to a lot of people. This can be shown by the contribution of this blog. 5 minutes ago it was at 713 and now it is 683. I think that this round should be unrated

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

      Its correct.Cheaters solved a,b,c easily.and someone can't solved B with their hard work. So By result cheaters got positive rating and hard worker got negative rating . It's unfair (

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

i solved e2 but i didn t understand problem b:))

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

Wow, Problem F is really constructive. Are there any easy solutions to F? I tried to implement the Segment Tree, but it is too hard (at least in my case)

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5 years ago, # |
  Vote: I like it +43 Vote: I do not like it

B should have tag unreadbale instead of math.

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

    The statement for B was very confusing.For the whole contest, I thought that every week that divides the total number of days given, results only in one pattern.

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

So beneficial a round to SegTree-addicts.

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5 years ago, # |
  Vote: I like it +39 Vote: I do not like it

Thanks for writing the round OP. I hope you don't take the hate comments too personally. I especially liked problem E, thought it was a very neat way of combining primes factorization with sorting/arrays.

Hope you can release more rounds and/or problems like this one :)

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

I solved A, B & C in under 30 mins but still, I would say the quality of problems especially B was not good. It was just observation, If you see it you solve it else keep getting more confused reading the statement.

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

whats the need for 6 green ticks. Just show 4 diff figures. so confusing,

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

Can someone hack this submission for E2? This shouldnt work as i only checked if the values were 0, p or 2p.

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

Problem statement for B is not well written...maybe same for E1

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

Increasing the difficulty of a contest just by making questions very big and confusing is just not done. It makes contest rubbish rather than difficult.

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5 years ago, # |
← Rev. 2   Vote: I like it +95 Vote: I do not like it

We don't need that frequent contests with that trash problems. Improve the quality of the problems.

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5 years ago, # |
← Rev. 2   Vote: I like it -9 Vote: I do not like it

A-B-C were one liners and completely math and observation based.I don't think math based problems are bad but I think at max 1 math based problem is enough for each contest. You shouldn't just be keeping the first 3 problems math based and then on top of that give an easy D problem.

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

I don't like problem B

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

Failed horribly and didn't learn a single thing from this contest.

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

Wasted a lot of time on B :( and if the answer is 4 why were there only 3 green ticks in diagram ?

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

Was I the only one who got a PDF statement for the 1371B - Magical Calendar during the contest?

I was kinda shocked seeing that O_o

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5 years ago, # |
  Vote: I like it +48 Vote: I do not like it

I got more confused by the green ticks than the language of B.

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    5 years ago, # ^ |
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    I was confused with parallel moves and didn't see the announcement for a while.

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      5 years ago, # ^ |
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      It is written parallel to the calender's sides so that was clear for me.

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

The statement of question B was unclear and the figure made it even worse.

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

I solved the 1st Q in 2 minutes.. 2nd Q in probably an hour and 3rd Q in 5-6 minutes.. The problem statement was very confusing physics0523

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5 years ago, # |
  Vote: I like it -77 Vote: I do not like it

The round was good. B could've been better.

To the incompetent motherfuckers who think the round was bad, go shove your green/grey/cyan/sexpert ratings up your asses. You are stupid and incompetent, just like me, but at least I am not bitching out here like you assholes. Accept you are pathetic and improve yourself. Your opinion doesn't even count as a div 2 rat, douchebags.

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    5 years ago, # ^ |
      Vote: I like it +55 Vote: I do not like it

    Hi. Which am i among "green/grey/cyan/sexpert"?

    I think people who complained about round quality (in discord servers, not only in CF comments) have logical and valid elaborations on why they think they are bad. I think they would be willing to discuss with you if you would ask them about which problems are good/why. I think it is not nice to call people "incompetent motherfuckers" if they are trying to engage in a rational discussion based on facts.

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      5 years ago, # ^ |
        Vote: I like it -51 Vote: I do not like it

      I don't want to engage in rational discussions with grey people. They tend to have different(read stupid) rationality.

      What are their points, huh? Too much math? Too much observation? This wasn't math. And observation isn't bad, it's good. These people don't know a dime about anything. They just performed shit, and started their stupid rant.

      I ask you, alright, tell me, what was bad in the round besides issues with B's statement?

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

        this comment was garbage.

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          5 years ago, # ^ |
            Vote: I like it +45 Vote: I do not like it

          Hello

          1) The fact that someone leaked solutions isn't author's fault. I will wait till someone leaks solutions when you host the round to tell that the round was terrible because of cheating.

          2) It's weird to accuse round in being "purely math" if later you tell that you didn't even have a chance to spend time on C or D. E2 and F were purely algorithmic. The only point where I may agree is B's statement.

          3) Competitive programming isn't entirely about knowing algorithms, thinking problems are good. Also, if you say that this round is pure math, please tell which round isn't pure math.

          This round wasn't one of the worst on CF, and I hope you can recognize that

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

        Listen You ASS****!,grey people like me perform bad in every round but dont rant afterwards .This round was genuinely bad.

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

    Dude, you need to take some lessons on improving your language. Just as you have your opinion, so do others, who are "complaining". Atleast, they are not using such profane language.

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

why ranting on the problem statement tho.. ? i also have hard time to understand it.. but the fact that a lot of people solve A-D under 1 hour, proving that the statement isn't that bad.. dont blame others just because you dont understand things.. what you need is practice..

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5 years ago, # |
← Rev. 3   Vote: I like it +22 Vote: I do not like it

Editorial is out! Auto comment: topic has been updated by physics0523 (previous revision, new revision, compare).

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

My first submission for problem A in C++ was

ceil(1.0 * n / 2) and got WA.
Does anyone have any idea what is wrong?

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

    ceil is not that accurate with large numbers..here it can go upto 10 power 9....so better to use (n+1)/2 instead of ceil...i also got one penalty in it as i also used ceil in the first go

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      5 years ago, # ^ |
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      it is not that it is not accurate but you have to typecast you can look my submission

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        5 years ago, # ^ |
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        i looked at your solution.... the only difference was that i wrote as follows: cout<<ceil(1.0*n/2)<<endl; ans your was like: cout<<ceil(n*1.0/2)<<endl; so what is the difference b/w the two your got ac but mine showed wa

        edit: i got my mistake..i directly printed the ceil(1.0*n/2) value instead of storing it in a long long variable.

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

    maybe because it is printing something like 1.06657e+06.

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      5 years ago, # ^ |
        Vote: I like it +3