Another Contest 8

Hello, welcome to a DMOJ contest! To celebrate the release of Elo-MMR, we're glad to invite you to another contest! Here are the parameters of the contest:

  • Contest duration: 2 hours.
  • Number of problems: 6, full feedback. Each problem is worth one point.
  • This contest will be rated for all previously unrated users and all users with rating at most 2399.
  • Scoreboard will be hidden.
  • Contest format: AtCoder format, no wrong submission penalty. Ties will be broken first by the number of points you have, and second by the time of your latest first AC on a problem.
  • Number of submissions allowed per problem: 25.
  • Checkers for problems: Unless otherwise specified, identical. The contest will follow the standard convention of having all lines terminate in a \n character.
  • Testers for this contest: dawnstar63, gs14004, koosaga, maxcruickshanks.

Clarification requests for the contest must be routed through the clarification system provided on DMOJ, and not through other channels including but not limited to Discord, Messenger, or Slack. Furthermore, all clarification requests will be handled the way they normally are in IOI. Note that, in particular, clarification requests must come in the form of yes/no questions. Responses to questions will consequently be one of the following:

  • Yes.
  • No.
  • Answered in task description (explicitly or implicitly).
  • Invalid question.
  • No comment.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in your performance being disqualified and pushed to the bottom of the scoreboard. Such behavior includes, but is not limited to:

  • Registering for the contest with at least two accounts.
  • Participating in the contest with an account that is not one's primary account.
  • During the contest window, talking about the contest in more detail than answering a yes/no question about whether one participated in the contest.
  • Attempting to exploit bugs in the platform to subvert the constraints of the contest.

Before the contest date, you may wish to check out the tips and help pages.

The contest consists of 6 questions with a range of difficulty. It is highly recommended to read all of the problems - problems are presented in roughly increasing order of difficulty. You will have 2 hours to complete the contest. After the contest window begins, you may begin at any time. Your personal timer will start counting down, and you will be able to submit until 2 hours from when you started, or until the hard deadline, whichever comes first.

After joining the contest, you proceed to the Problems tab to begin. You can also go to Users if you wish to see the rankings.

We have listed below some advice as well as contest strategies:

  • Start from the beginning. Ties will be broken as specified at the top of the contest description.
  • Remove all extra debugging code and/or input prompts from your code before submitting. The judge is strict — your output must match the judge output exactly unless stated otherwise.
  • Do not pause program execution at the end. The judging process is automated. You should use stdin / stdout to perform input / output, respectively.
  • It is guaranteed that all the problems will be solvable with C++. All judge solutions run in at most 50% of the time limit, without using non-standard fast I/O methods.

At the end of the contest, you may comment below to appeal a judging verdict. In the case of appeals, the decision(s) of our staff is final.


  • 2
    luismo  commented on Aug. 30, 2021, 9:30 a.m.

    Can we share some code here? I thinks editorials could be more explaning with code. Thanks in advance

    • 8
      xiaowuc1  commented on Aug. 30, 2021, 2:43 p.m.

      Sharing code on DMOJ is generally disallowed - because problems are weighted and there's a ranking of users by the problems they solve, dishonest users will find code that is published on DMOJ or on other websites to inflate their ranking.

      Most editorials that I write on DMOJ provide a high-level sketch and ask the user to figure out the details on their own - this is mostly to provide a learning opportunity as opposed to just spoiling the problem completely. Enough details are provided that someone who is appropriately positioned to upsolve the problem will be able to figure out the rest on their own. If someone is still confused after reading through the editorial, it is likely that the user is missing some prerequisite knowledge and should return to the problem at a later point in time.

  • 2
    Viv_CCGS  commented on Aug. 26, 2021, 8:14 a.m.

    Are all the problems solvable with Python 3?

    • 12
      xiaowuc1  commented on Aug. 26, 2021, 11:00 p.m.

      Short answer: I don't know.

      Long answer: All reference solutions are written in C++ and time limits are set so that the reference solutions run in at most 50% of the time limit. This is why we can promise that the problems are solvable in C++ (because the reference solutions are in C++). The problems may be solvable in other languages, and the 50% time limit buffer is designed to help support that, but we do not promise that any other language (including Python) can be used to solve all the problems.

      • 2
        Viv_CCGS  commented on Aug. 28, 2021, 10:17 p.m.


  • -9
    doesy5  commented on Aug. 20, 2021, 8:35 p.m.

    This comment is hidden due to too much negative feedback. Click here to view it.

  • 31
    thomas_li  commented on Aug. 17, 2021, 11:35 a.m.