DMOPC '20 March Contest

Welcome to the fourth DMOJ Monthly Open Programming Competition of the 2020-2021 season!

The problem writers this time are Riolku, AvaLovelace, 4fecta and WallE256.

This round will be rated for all participants.

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

This contest will consist of 6 problems, the difficulty of which may range anywhere from CCC Junior to CCO level.

Some problems offer partial marks in the form of subtasks. If you cannot solve a problem fully, we encourage you to go for these partial marks.

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 EDT of March 15th), 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:

  • Ties will be broken by the sum of last submission times that increased score.
  • Problems will be approximately increasing in difficulty. Reading all of the statements is still recommended.
  • 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.
  • 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++, Java and Python.

Unlike previous DMOPCs, the identical checker will be used for all problems unless specified otherwise. The contest will follow the standard convention of having all lines terminate in a \n character, with no trailing whitespace.

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:

  • 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.

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.


  • 2
    Kirito  commented on May 3, 2021, 4:33 a.m. edit 2

    Ratings for DMOPC 2020-2021 Contest 4 have been finalized. If you wish to dispute your rating, please email us at contact -at- dmoj -dot- ca, or message us on the DMOJ Discord.

  • 8
    Encodeous  commented on March 12, 2021, 4:44 p.m.

    Good Luck!

  • 0
    Quads  commented on March 12, 2021, 6:41 a.m.

    Is this rated on join?

    • 3
      Riolku  commented on March 12, 2021, 5:33 p.m.

      The description has been clarified. The round is rated on join.

    • -4
      maxcruickshanks  commented on March 12, 2021, 4:40 p.m.

      Yes: This round will be rated for all participants.

      • 3
        dxke02  commented on March 12, 2021, 4:41 p.m.

        I think he means to ask whether you need to make a submission to be rated or you are automatically rated upon join regardless of how many submissions you make.

  • 13
    4fecta  commented on March 12, 2021, 5:49 a.m.

    I would like to proudly announce that 1 out of 6 problems on this contest supports a full Japanese translation. If you would like to view it, please change the site language to Japanese when reading the problem (the button to do that can be found at bottom of the DMOJ page).

    お知らせ: このコンテストに、1 つ問題は日本語の翻訳があります。ご覧になりたい方は、サイトの言語を日本語に設定してください(DMOJ ページの下でボタンがあります)。


    • 19
      EpicChadGamer  commented on March 12, 2021, 9:59 p.m.

      Stop speaking korean

    • 3
      ManchurioX  commented on March 12, 2021, 6:01 a.m.

      DMOJ to compete with AtCoder for best Japanese OJ?

    • 3
      ManchurioX  commented on March 12, 2021, 5:54 a.m.


  • 8
    Riolku  commented on March 11, 2021, 3:09 a.m.

    All problems are now guaranteed to be solvable in Python, Java and C++.

  • 5
    Riolku  commented on March 10, 2021, 4:20 a.m.

    The contest format has been updated. Ties will be broken by the sum of last submissions times that increased score.

    • 3
      Riolku  commented on March 10, 2021, 8:49 p.m.

      The description has been clarified to reflect this comment.

  • -7
    Badmode  commented on March 8, 2021, 11:52 p.m.

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

    • 8
      dxke02  commented on March 9, 2021, 2:08 p.m.

      Only if you solve the problems!