DMOPC '20 April Contest

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

The contest organizer this time is Riolku.

The problem writers this time are AvaLovelace and 4fecta.

Thanks to Dormi, AQT, ChrisT, JoshuaL, DM__Oscar, maxcruickshanks, dxke02, lookcook, kdrkdr, Zeyu and kevinyang for testing and feedback on problems.

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 April 26th), 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++.

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.


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

    Ratings for DMOPC 2020-2021 Contest 5 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.

  • 0
    asifalim  commented on April 27, 2021, 5:11 p.m.

    how I can see code for a particular problem of another users?

    • 9
      verybadallen  commented on April 27, 2021, 5:23 p.m.

      Step 1: Solve the problem.
      Step 2: Click All Submissions on the top right of the page, under the Submit solution button.
      Step 3: If you've solved the problem and received AC verdict, you will be able to see a view link next to any submission to the problem. Click it.
      Step 4: Click the View source link that will be on the top left side of the submission page. You will now be able to see code for a particular problem of another user(s).

      Hope this helps.

    • 1
      Kirito  commented on April 27, 2021, 5:19 p.m.

      By solving said problem.

  • 8
    AlexC  commented on April 21, 2021, 11:12 p.m.

    Do I have to sign up?

    • 7
      Badmode  commented on April 22, 2021, 1:13 a.m.

      No, the only requirement is to have a DMOJ account.

  • 11
    vishnus  commented on April 20, 2021, 12:33 p.m. edited

    orz dxke02, now you can finally add "DMOJ Problem Setter" to your resume!

    • -16
      dxke02  commented on April 20, 2021, 1:07 p.m. edit 2

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

      • -14
        rexn  commented on April 20, 2021, 1:52 p.m.

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

        • 13
          vishnus  commented on April 20, 2021, 2:16 p.m.

          please downvote me. I want to get ratioed

  • 9
    slightlyskepticalpotat  commented on April 20, 2021, 3:20 a.m.

    When the DMOPC is in the correct month...

    • 6
      Badmode  commented on April 20, 2021, 4:40 a.m.

      Well, only two DMOPC contests were not in the correct month, out of all the DMOPC contests.