Welcome to PIB '20!

Here are the parameters of the contest:

  • Contest duration: 4 hours.
  • Number of problems: 7, NO feedback, with subtasks.
    • Each problem will be worth 100 points.
    • Problems are not guaranteed to be in order of difficulty.
    • Time limits and memory limits will be set to at least 2.5x the author solution, which is written in C++.
    • Details on the no feedback format will be described later.
  • Format: ECOO.
    • In particular, the last submission will be used in determining your score.
    • There will be no first AC bonus or time bonus.
    • Ties will be broken by the sum of last submission times.
  • Rated for users who submit at least once.
  • Scoreboard will be hidden.
  • No submission limit.
  • The problem writers for this contest are Ninjaclasher, Dormi and JoshuaL.
  • The problem testers for this contest are ChrisT, Plasmatic, zxyl, and Beautiful_Times.

No Feedback Format

During the contest, you will not be judged on any of the test data, only the sample test cases. Each subtask of every problem will have exactly one sample to represent it. After the contest, your submission will be judged on all the test data. Only the last submission will be used to determine your score, so ensure your last submission is your final solution. Some solutions may pass the samples and receive all the pretest points, though they may not pass all the test data. It is therefore recommended to test your code locally.

Due to rampant issues with cheating on contests that has happened recently, any suspicious behavior during the contest window may result in being forcibly ranked at 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 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 subvert the constraints of the contest, including but not limited to, exploiting bugs in the platform.

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

The contest consists of 7 questions with a range of difficulty from CCC Senior to IOI. It is highly recommended to read all of the problems. You will have 4 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 4 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:

  • 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.
  • 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++.

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.


  • 4
    ElyesChaabouni  commented on March 17, 2020, 4:34 p.m.

    Will there be an editorial?

  • -1
    hloya_ygrt  commented on March 17, 2020, 3:20 p.m.

    where can i find my submissions?

    • 2
      Ninjaclasher  commented on March 17, 2020, 3:28 p.m.

      Once we release the problems, you will be able to access your submissions from the main site. For now, you can "Virtual Join" the contest to view your submissions.

  • 6
    ElyesChaabouni  commented on March 14, 2020, 5:58 p.m.

    What do the initials PIB stand for?

    • -12
      harry7557558  commented on March 14, 2020, 9:49 p.m. edit 4

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

      • -6
        CheezWhiz  commented on March 15, 2020, 8:03 p.m.

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

    • -3
      kdrkdr  commented on March 14, 2020, 6:47 p.m.

      penguins in berlin

  • 33
    bqi343  commented on March 10, 2020, 7:48 p.m.

    There's no point in doing a contest without feedback ...

    • 13
      rpeng  commented on March 11, 2020, 12:51 p.m.

      Tell that to the ECOO organizers...

      Does ECOO still grade by running a CD to your machine by the way?

      • -8
        Dan13llljws  commented on March 14, 2020, 2:23 p.m.

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

      • 9
        rjamieson100  commented on March 12, 2020, 8:49 p.m.

        Teacher here. We give feedback at ECOO. # AC and then teams can write down correct answers from 1st test case.

      • 9
        Beautiful_Times  commented on March 11, 2020, 1:59 p.m.

        They ran a usb to our machine last year

    • 12
      Ninjaclasher  commented on March 10, 2020, 9:33 p.m. edited

      I apologize for the confusion; you will receive feedback on the sample cases, but will not be receiving feedback on the remainder of the test cases until after the contest ends.

      If you meant no feedback contests in general, many OI contests don't give feedback besides samples (like the COCI and the Chinese NOI). Also, it is good practice for ECOO (which many Ontario high school students participate in), as they only allow 2 submissions with different test data per submission. Although they do give feedback, this is probably the closest that can be emulated on the DMOJ, as DMOJ does not currently support changing data between submissions.

  • 12
    HyperNeutrino  commented on March 9, 2020, 9:58 p.m.

    no feedback

    judge is strict