DMOPC '21 February Contest

Welcome to the sixth DMOJ Monthly Open Programming Competition of the 2021-2022 season!

The contest organizers this time are 4fecta, Riolku, and zhouzixiang2004.

UPDATE: Thanks for writing the contest! The contest authors this time were 4fecta, AvaLovelace, and Riolku.

Thanks to Nils_Emmenegger, ThingExplainer, Tony1234, uselessleaf, WilliamWu277, and wleung_bvg for testing and feedback on problems.

This round will be rated for all participants.

As the round is intended to follow a mock CCC Senior format, there are some differences in the contest specifications from previous DMOPCs.

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

This contest will consist of 5 problems, the difficulties of which will approximately range from CCC Senior 1 to CCC Senior 5.

You will have 3 hours to complete the contest. After the contest window begins, you may begin at any time. Once you enter the contest, your personal timer will start counting down and you will be able to submit until 3 hours from when you started, or until the hard deadline (00:00:00 EST of February 15th), whichever comes first.

After joining the contest, you proceed to the Problems tab to begin.

Here are the parameters of the contest:

  • Some problems offer partial marks in the form of subtasks.
  • Ties will be broken by the maximum submission time that increased score with no penalties.
  • A maximum of 50 submissions will be allowed per problem.
  • Scoreboard will be hidden, until your window is over. Divulging the contents of the scoreboard to participants who have not finished their window is an offense, the punishments of which are listed below.
  • Problems will be approximately increasing in difficulty, and will all have full feedback. Reading all of the statements is recommended.
  • Checkers: unless otherwise specified, standard.
  • Interactors: unless otherwise specified, assume that all interactors are not adaptive.
  • Rated for opening the contest. Being able to read the problems will cause the contest to be rated.
  • It is guaranteed that all the problems will be solvable with C++, and all time limits will be at least 2x the runtime of the reference solution.

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

  • Remove all extra debugging code and/or input prompts from your code before submitting. The judge is very strict — most of the time, it requires your output to match exactly.
  • Do not pause program execution at the end. The judging process is automated. You should use stdin / stdout to perform input / output, respectively.
  • Python users are recommended to use PyPy 2/3 over Python 2/3 when submitting.

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 and 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.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in your rating being impacted negatively. Such behavior includes, but is not limited to:

  • Divulging the contents of the scoreboard to participants who have not finished their window.
  • Registering for the contest with at least two accounts.
  • Participating in the contest with an account that is not your 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. This includes, but is not limited to, posting spoilers about the contest and public speculation of the contest.
  • Attempting to exploit bugs in the platform to subvert the constraints of the contest.
  • Attacking the judge infrastructure, other contestants, or contest personnel within or after your window.

Punishments may include performance being unrated or, for more serious infractions, being forcibly ranked at the bottom of the scoreboard.

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


  • 1
    WSM_simon  commented on Feb. 26, 2022, 1:59 p.m.

    Where is DMOPC '21 Contest 6 P4 - Colourful Paths?

    • 4
      Riolku  commented on Feb. 26, 2022, 5:22 p.m.

      The problem had issues with data and I forgot to fix them. It's public now.

  • 6
    Lost  commented on Feb. 14, 2022, 7:59 p.m.

    Regular DMOPC: ~150-200 participants

    Mock CCC format: 300+ participants

    • 3
      Badmode  commented on Feb. 14, 2022, 10:24 p.m.

      Wish you a CCO invite

      • 1
        Lost  commented on Feb. 15, 2022, 8:36 a.m.

        you too 😩

      • 3
        vishnus  commented on Feb. 15, 2022, 8:23 a.m.

        Wish you high rating

  • 10
    sz_8  commented on Feb. 11, 2022, 6:01 p.m.

    Last minute CCC preparation. :D

  • -6
    dizmac  commented on Feb. 10, 2022, 8:36 a.m.

    This comment is hidden due to too much negative feedback. Show it anyway.

  • 5
    Plasmatic  commented on Feb. 7, 2022, 12:15 a.m.

    dmopc monthly open programming contest

    • 7
      Snowfall  commented on Feb. 7, 2022, 7:53 a.m.

      dmoj: modern online judge monthly open programming contest

      • 7
        Ronakße  commented on Feb. 7, 2022, 4:04 p.m.

        modern online judge monthly open programming contest judge online Annual Mock CCC Senior Contest modern online judge

  • 11
    ryanawad  commented on Feb. 6, 2022, 9:58 p.m.

    les poggeurs

  • 15
    X_Ray  commented on Feb. 6, 2022, 9:54 p.m.

  • 9
    psun256  commented on Feb. 6, 2022, 9:10 p.m.

    DMOJ Monthly Open Programming Contest

    DMOJ Annual Mock CCC Senior Contest

  • 14
    dawangk  commented on Feb. 6, 2022, 8:57 p.m.