CBOJ 2023 Welcome Contest

Welcome to Computing Club's 2023 Welcome Contest!

The organizers are ZahinAbrer, Nirdev_Paul, NamanB, NK, and andrewq.

You have \(120\) minutes or \(2\) hours to solve \(4\) problems, the difficulty of which ranges from CCC J1 to S2. Each problem is worth a total of \(100\) points. You can begin the contest at any time by clicking the "join" button. Once you've begun, your personal timer will begin to count down, and you'll be able to submit until \(2\) hours from when you started, until the hard deadline (11:59 PM EDT on October 23rd), or until you click the Leave Contest button, whichever comes first.

Once you've begun your contest, you can access the problems by clicking the problems tab on the top bar.

Feel free to familiarize yourself with contest mechanics by trying a past contest.

Additional Information:

  • Make sure you read all of the problems. There will be subtasks that allow you to get partial points, and every point counts.
  • Batch dependencies are enabled. You will be required to pass earlier subtasks in order to receive points for later subtasks.
  • All problems have been tested with C++ and Python.
  • Problems are approximately in increasing order of difficulty.
  • The scoreboard will be public.
  • In case of ties, the latest submission time that increased your score will be used as tiebreaker for this contest.
  • As with any contest, discussing contest problems before the contest end date is strictly prohibited. The only exception is the post-contest discussion channel in the club server, which can only be accessed once your 2-hour window is over.
  • Checkers: unless otherwise specified, standard.

Some extra advice:

  • 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.
  • Python users are recommended to use PyPy 2/3 over Python 2/3 when submitting, unless otherwise specified.
  • It is highly recommended to use fast input/output for your language. This means using BufferedReader for Java, and adding these two lines to your C++ code.

The following behavior is forbidden:

  • 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.
  • Attacking the judge infrastructure, other contestants, or contest personnel within or after your window.

Clarification requests for the contest must be routed through the clarification system provided on CBOJ, 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.

Good luck!


  • 1000000010
    JonathanZhu19  commented on Oct. 14, 2023, 3:39 p.m. edit 2

    Thx for making contest! orz execs