DMOPC '20 October Contest

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

The problem writers this time are richardzhang, Kirito, and AvaLovelace.

Please note that this contest will be full feedback.

This round will be rated for all participants.

Also, happy early Turkey Day! Statutory Holidays are great.

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 (23:59:00 EDT of October 12th), 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 last submission time that increased your score plus penalties. The first submission time of your highest score will be used.
  • Each non-AC (excluding Compiler Errors) submission will incur a penalty of 5 minutes.
  • It is not guaranteed that the problems will be in order of increasing difficulty. Reading all of the statements is 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.
  • It is guaranteed that all the problems will be solvable with C++.

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 Slack and Discord.

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.


  • 7
    Kirito  commented on Oct. 14, 2020, 11:47 p.m. edited

    We have found post-contest that there is an extra space at the end of the line on certain problems. If this issue affected your performance in-contest (namely Python users), please message either richardzhang or Kirito on Discord to request to be unrated.

  • 7
    richardzhang  commented on Oct. 14, 2020, 9:06 p.m.

    Editorials have been released, and P5 has been made public.

  • 11
    tehillah  commented on Oct. 12, 2020, 6:03 p.m.

    If you could notify the users of the upcoming contests it will be really helpful as some of us are not frequent visitors.

    • 36
      Tzak  commented on Oct. 12, 2020, 10:16 p.m.

      What is your address? I will send you a letter in the mail next time there is a contest.

      • 9
        randomperson89  commented on Oct. 13, 2020, 5:54 p.m. edited

        Just use a carrier pigeon. I'll personally send my carrier pigeon to everyone.

  • 16
    31501357  commented on Oct. 9, 2020, 2:46 p.m.

    This time I will actually do good.

  • 63
    Plasmatic  commented on Oct. 8, 2020, 12:35 p.m.

    my rating gone

    • -11
      Dan13llljws  commented on Oct. 14, 2020, 2:52 a.m.

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

  • 32
    Encodeous  commented on Oct. 8, 2020, 11:40 a.m.