ToniB's blog

Croatian Open Competition in Informatics (COCI) 2024/2025 — Round #3
By ToniB, history, 13 days ago, In English

Hi everyone!

The third round of COCI will be held tomorrow, December 7th at 14:00 UTC. You can access the judging system here. If you are not familiar with the COCI contest format, we encourage you to read the announcement.

The round was prepared by keko37, celin, fbabic, vito1036, psruk, mkisic and me.

Feel free to discuss the problems in the comment section after the contest ends.

Hope to see you tomorrow!

  • Vote: I like it
  • +41
  • Vote: I do not like it

»
13 days ago, # |
  Vote: I like it +22 Vote: I do not like it

MY FAVORITE OLYMPIAD!!!! I LOVE CROATIA!!

→ Reply
»
12 days ago, # |
  Vote: I like it 0 Vote: I do not like it

how difficult are the problems?

→ Reply
  • »
    »
    12 days ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    COCI problems have different scores usually. (more score, harder)

    • A : 50
    • B : 70/90
    • C<= : 110<=
    → Reply
    • »
      »
      »
      12 days ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      How would that compare to cf rating though?

      → Reply
      • »
        »
        »
        »
        12 days ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Why not just participate and see it yourself?

        → Reply
        • »
          »
          »
          »
          »
          12 days ago, # ^ |
            Vote: I like it +8 Vote: I do not like it

          Because i want to go play in a yugioh tournament, and i dont wanna skip the yugioh tournament to participate in a contest where i would solve 0 problems

          → Reply
          • »
            »
            »
            »
            »
            »
            12 days ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            I'm guessing you would at least solve 1-2 problems (maybe more) and get subtasks from others. Do whichever one feels more fun though :))

            → Reply
»
12 days ago, # |
  Vote: I like it 0 Vote: I do not like it

for Karte I have a code but im not sure it should work

code

I always take the M cards however there can be a case where one of the M cards is completely useless and dosent do a combo with any other card and thus is never optimal to take

→ Reply
»
11 days ago, # |
  Vote: I like it +7 Vote: I do not like it

How to solve E?

→ Reply
»
11 days ago, # |
  Vote: I like it +37 Vote: I do not like it

Image of clarification

Why is it not specified whether the grader is adaptive or not?? I believe it is very important for a question like this since randomized solution could exist. In fact, I think the grader is not adaptive because my solution is randomized (using quick select), and it obtained 75 points. If the grader was adaptive, my solution would probably have gotten 15/0 points. If someone decided not to implement his randomized algorithm because he assumed the grader is adaptive, it would have cost the person a lot of points.

→ Reply
  • »
    »
    11 days ago, # ^ |
      Vote: I like it -10 Vote: I do not like it

    Hi, the grader is not adaptive, and you are right.

    I didn’t include it in the statement because I didn’t anticipate that a solution could pass under much tighter constraints using quickselect. The intended solutions for each subtask are entirely deterministic.

    Normally I would assume the grader is adaptive if not specified, but the assumption would've been wrong here. We apologize for the inconvenience.

    → Reply