The triennial (?) UTS Open contest is back with a fresh set of problems! We tried to make all the problems school themed, but that ended up being too cringe so this problem set is what we ended up with. You may or may not notice a certain pattern in the problem titles, which may or may not have been intentional. We're not quite sure ourselves either.

Regardless, we truly hope you enjoy the problems of UTS Open 2021! With that being said, here are the parameters of the contest:

  • Contest duration: 3 hours.
  • Number of problems: 7, full feedback. Each problem will be worth 100 points, with some problems offering partial marks in the form of subtasks.
  • Rated for opening the contest. Unlike with other contests which require making a submission for the contest to be rated, opening the contest and being able to read the problems will cause the contest to be rated.
  • Scoreboard will be public.
  • 50 submission limit per problem.
  • Ties will be broken by the last submission time that increased your score. The first submission time of your highest score will be used.
  • The contest will follow the standard convention of having all lines terminate in a \n character, with no trailing whitespace.

Furthermore, users are forbidden from using multiple accounts or collaborating during the entire contest duration. Any suspicious behaviour during the contest window may result in a severe penalty including, but not limited to, being placed at the bottom of the scoreboard. Such behaviour 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.

The problem setters for this contest are 4fecta, zxyl, Dormi and glasa.

Special thanks to AQT, Aaeria, Riolku and JoshuaL for providing feedback and testing the problems.

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

This contest will consist of 7 problems with difficulty ranging from CCC Junior to CCO level.

You will have 3 hours to complete the contest. After the contest window begins (February 5th, 12:00 AM EST), 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 (February 7th, 23:59 EST), whichever comes first.

After joining the contest, you can 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:

  • 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++. All problems have a time limit of at least 2x the reference solution, which is written in C++ and uses this template for I/O. If you're unable to see the template, you must solve this problem. Problems that have been tested in multiple languages may have language specific time limits.

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.


  • -1
    Kirito  commented on Feb. 26, 2021, 7:14 p.m. edit 2

    Ratings for the UTS Open '21 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.

    • -1
      d3story  commented on Feb. 27, 2021, 6:56 p.m. edited

      I want to know why my results for this contest were reduced to -9999. Am I not allowed to end the contest early?

      Wait nvm wrong contest. but can someone give me an answer?

      • 1
        Kirito  commented on Feb. 27, 2021, 6:59 p.m. edit 2

        I'm assuming you're referring to this contest.

        You were disqualified for having code that too closely matches another contestant. If you wish to dispute your disqualification, please email us at contact -at- dmoj -dot- ca, or message us on the DMOJ Discord.

  • 0
    Sanzhuk  commented on Feb. 9, 2021, 2:50 a.m.

    Will be editorial posted?

  • -1
    HyperGraphJ  commented on Feb. 8, 2021, 4:26 p.m.

    Problem 2 was pretty rough grading, I believe my code only failed right at the upper bound for N because I forgot to make use of 1s.

    • 13
      verybadallen  commented on Feb. 8, 2021, 4:38 p.m.

      That's an error with your code, not the grader lol

      • -4
        HyperGraphJ  commented on Feb. 8, 2021, 6:59 p.m.

        Sure no doubt, just kind of unpleasant to have a corner case negate 100% of pts, but it is what it is.

  • 5
    Kirito  commented on Feb. 8, 2021, 5:23 a.m.

    Preliminary ratings for UTSO are out. This post will be updated once ratings are finalized.

  • 6
    ngkimphuongtrang  commented on Feb. 8, 2021, 5:22 a.m.

    How can I be rated? I solved 1 problem in this contest but finally I don't see my rating. It's just nothing. I'm new to DMOJ. Sorry for my poor English. Thanks a ton.

    • 5
      4fecta  commented on Feb. 8, 2021, 5:49 a.m.

      You've been rated now, congrats!

      • 10
        d3story  commented on Feb. 8, 2021, 5:55 a.m.

        Quick question, when will the editorials be out?

  • 6
    Chinomso  commented on Feb. 7, 2021, 10:29 p.m.

    I solved one problem and got 100 but how do I view the rest, I'm new to dmoj and time is running out!!

    • 9
      wleung_bvg  commented on Feb. 7, 2021, 10:37 p.m.

      If you go to the problems tab near the top left corner (while in the contest), you should be able to see all the problems in this contest.

  • 15
    Kirito  commented on Feb. 6, 2021, 11:37 p.m. edited

    Due to a bug with the DMOJ site, rating changes may appear before the end of the contest. THIS IS A BUG and ratings will be recomputed at the end of the contest.

  • 31
    4fecta  commented on Jan. 29, 2021, 4:20 a.m.

    After some discussion amongst the problem setters, we have decided to remove the incorrect submission penalty from this contest. This means that incorrect solutions will no longer affect your time penalty on the contest scoreboard. Please keep this change in mind moving forward!

  • 24
    Eason_Hao1019  commented on Jan. 27, 2021, 10:05 p.m.

    Is there any practicing question for this contest?

  • 17
    Encodeous  commented on Jan. 26, 2021, 2:25 p.m.

    Good luck everyone!

  • 20
    dxke02  commented on Jan. 26, 2021, 12:47 a.m.

    Wow, 2 rated contests in 2 weeks

    • 8
      Subway_Man  commented on Jan. 26, 2021, 7:59 p.m.

      When it rains, it pours~

  • 11
    DM__Oscar  commented on Jan. 26, 2021, 12:39 a.m.

    Goodbye, purple rating :(

  • 11
    Badmode  commented on Jan. 25, 2021, 5:58 p.m.

    Is this contest recommended for everyone?

    • 9
      noYou  commented on Jan. 26, 2021, 2:38 a.m. edited

      This contest will consist of 7 problems with difficulty ranging from CCC Junior to CCO level.

      Assuming "everyone" can at least attempt a CCC junior problem, yes.

      • 11
        Badmode  commented on Jan. 26, 2021, 2:46 a.m.

        Thank you for clarifying.

    • 18
      Blackgaurdian3  commented on Jan. 26, 2021, 12:35 a.m.

      There's no harm in giving it a try