Mock CCC '20 Contest 2 Senior

Ninjaclasher was bored the past 3 days, so he decided to make a mock CCC. He also roped in Beautiful_Times for a problem because, you know, sometimes you just can't solve your own problem.

Here are the parameters of the contest:

  • Contestants must write the mock CCC under CCC rules. Notably, contestants may not consult the Internet outside of accessing the relevant parts of the contest via the DMOJ platform or consulting language documentation, and contestants may not use any prewritten code.
  • Contest duration: 3 hours.
  • Number of problems: 5, full feedback, with subtasks. The problems follow the CCC format of being worth 15 marks each. Some problems may have explicit subtasks.
  • Format: IOI (no penalties, no tiebreakers)
  • Not rated.
  • Scoreboard will be hidden.
  • Number of submissions allowed per problem: 50.
  • The problem writers for this contest are Ninjaclasher and Beautiful_Times

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. 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 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 exploit bugs in the platform to subvert the constraints of the contest.
  • Not following the CCC rules.


  • The difficulty of the contest is approximately the difficulty of the CCC senior. However, we do not guarantee that they are the same difficulty.
  • We do not guarantee that all problems can be solved with only topics and concepts allowed in the IOI syllabus.
  • Problems 3 to 5 may not be of increasing difficulty. It is therefore recommended to read all the problems.

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

The contest consists of 5 questions with a range of difficulty from CCC Senior 1 to CCC Senior 5. It is highly recommended to read all of the problems. You will have 3 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 3 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++. We do not guarantee that all problems are solvable in C, Java, or Python.

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.


  • 2
    Narcariel  commented on Feb. 26, 2020, 4:26 p.m.

    Why are the questions not on DMOJ?

  • 2
    leonzalion  commented on Feb. 11, 2020, 5:50 p.m.


    • 0
      kevinyang  commented on Feb. 11, 2020, 8:51 p.m.


    • 0
      GeeTransit  commented on Feb. 11, 2020, 8:33 p.m.


  • 21
    Aaeria  commented on Feb. 11, 2020, 4:16 p.m. edit 3

    Good luck on CCC!

    (reply to make cco)

    • 3
      devnarula  commented on Feb. 12, 2020, 12:58 p.m.

      good luckkkkkkkkkk

    • 7
      Plasmatic  commented on Feb. 12, 2020, 9:38 a.m.


    • -5
      AQT  commented on Feb. 12, 2020, 6:42 a.m.

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

    • 3
      eijijo  commented on Feb. 11, 2020, 11:13 p.m. edited


    • 17
      Chess1000  commented on Feb. 11, 2020, 4:48 p.m.

      Thanks! You too.

      • -10
        Hubie  commented on Feb. 11, 2020, 6:36 p.m.

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

      • 17
        Tzak  commented on Feb. 11, 2020, 6:26 p.m.

        Thank you! Best of luck to you too :)

        • 6
          p1geon  commented on Feb. 11, 2020, 9:14 p.m.

          glhf! :)

          • 17
            qiuxinrong27  commented on Feb. 11, 2020, 9:44 p.m.

            GLHF! :) (Upvote to make CCO)