lior5654's blog

[Discussion Thread] APIO 2021
By lior5654, history, 4 years ago, In English

As Israeli contestants posted both the APIO 2019 Discussion Thread & the APIO 2020 Discussion Thread, I feel obligated to post this year's discussion thread :D

This year, APIO 2021 is hosted again by Indonesia. For most of the participating countries, APIO 2021 serves as one of the main "TST"s (Team Selection Tests) for IOI 2021 (including Israel). The competition's official website is located Here.

The competition is IOI style, 5 hours long. A maximum of 50 submissions is allowed for each problem. A participant's final score is the sum of the scores the participant got on each problem. A participant's score for a problem is the sum of the scores the participant gained in each subtask of the problem. A participant's score for a subtask is the maximum grade the participant's submissions achieved for that subtask.

APIO Problems are of high quality and are considered good practice for those who wish to participate in IOI.

This thread is intended for discussing results. Furthermore, after APIO 2021 Open Contest ends, this thread shall also be used for discussing the solutions to the problems given in the competition.

Note: Before jonathanirvings writes a comment like this yet again, please note that discussing solutions before APIO 2021 Open Contest ends is prohibited. However, discussing results should be allowed as the official window (based on the official website) has ended.

  • Vote: I like it
  • +67
  • Vote: I do not like it

Comments Comments (33)
| Write comment?
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Auto comment: topic has been updated by lior5654 (previous revision, new revision, compare).

→ Reply
»
3 years ago, # |
  Vote: I like it +45 Vote: I do not like it

Israel results: 236 187 126 85 82 82 82

I got 126.

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Does anybody know where to find the unofficial results?

→ Reply
»
3 years ago, # |
← Rev. 3   Vote: I like it +120 Vote: I do not like it

Do not see the former versions!!!

→ Reply
»
3 years ago, # |
  Vote: I like it +8 Vote: I do not like it

What is the cutoff for each medal in unofficial results?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    84 137 209

    Hard contest.

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +5 Vote: I do not like it

      Please tell me this is wrong I got 81 I could have solved subtask 3 and 4 Roads easily, But they seemed impossible at first glance, that I didn't even think about them :( I just left them!!! Are you Sure bronze medal cutoff isn't 81 XD How did you know it's 84?? Do you have the results?? Is it possible to see them?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +6 Vote: I do not like it

        Not wrong according to the unofficial results. I had 126, 66th place out of officials, 1 subtask away from silver -_-.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +5 Vote: I do not like it

          I'm sure you can solve another subtask.... Silver medalist ;) What bad luck! Anyway, can you tell me my rank? PSE03

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
            ← Rev. 4   Vote: I like it 0 Vote: I do not like it

            119 1 PSE03 Nicola AbuSaad Palestine 9 60 12 81

            you got 119th, bronze is atmost 108th :(, ignore the previous revisions I misread your grade

            → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it +10 Vote: I do not like it

            Bronze, not Silver. Everyone almost always feel that they could've done better, that's a part of the game :)

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

              Thanks bro anyway for the info, As a conclusion we have the following theorem XD,

              Theorem: given a set of subtasks, the best thing to do is to think of a solution for every single subtask that belongs to the set, without ignoring any subtask.

              Proof is left as an exercise to the reader.

              See you bro at IOI 2021 :)

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

        sad. I also was able to ez get 86 with 5 points in C. But I just focused on B and got 0 in C. I got 81 points only :/

        → Reply
»
3 years ago, # |
  Vote: I like it +26 Vote: I do not like it

As a chinese participant, I needed to wait for 10 minutes after each submission. I thought that the delay was normal and just sat and waited. But strange things happened after 12:00 pm, 3 hours after we started the contest. We cannot get result anymore, and our submission led to endless "compiling" sign. After 1 am, 4 hours after the contest, I tried to submit my A and C, but the system threw the error "submission storage error". I had typed the B=0 solution of A, which can get 30+ points of A. But all these codes became useless. After the contest had ended, I just got 25 points from problem B, but I think I can get greater than 100 points if I could submit A and C.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    The Chinese Mirror Contest is really disgusting......

    long queue -> site down -> server error

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

    What a pity!

    But isn't the website problem caused by the organizer of Indonesia?

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

      In short, the Indonesia server and the judge machine led to the long queue, and the long queue led to rejudge and endless "compiling" sign.

      → Reply
»
3 years ago, # |
  Vote: I like it +10 Vote: I do not like it

0+100+100

I had no time to get 9 points in the first problem :(

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

we can submit but can't see score in last 2 hours - Vietnam :<

→ Reply
»
3 years ago, # |
← Rev. 8   Vote: I like it +58 Vote: I do not like it

come on guys, you have to do something for contestants scoring 82

5 of them are in the first half but because there are equal scores they all got nothing. with all the issues in this contests, like the long queue that took a lot from our contest time and not to mention Problem C which is the exact same as a CF problem

Please you should consider giving those guys bronze medals just like in APIO 2019, 2017 and 2015.

And contestants who got 82 please try to do something with your leaders. prabowo jonathanirvings

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Hi, if I start my timer after midnight, will the competition end for me at 5:00 or will I be able to continue past that time, until my 5 hours are up?

→ Reply
»
3 years ago, # |
  Vote: I like it -27 Vote: I do not like it

It's over, and we are finally allowed to say roads is 1119F - Niyaz and Small Degrees.

Quite interestingly, a lot of Chinese accounts started submitting solutions to this particular problem on May 22nd. The last submission before the contest window was on May 5th. Good job authors!

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    "Each contestant is allowed to use any sources of information on the Internet"

    The rule is very clear.

    And the problem is too easy to find... though I found it after I solved it... So I submitted it a second time, and it annoyed me a lot because of the difference between the constraints.

    And please don't make your username too unfriendly. I don't think it's a good behavior.

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
      ← Rev. 2   Vote: I like it +20 Vote: I do not like it

      Of course the most to blame is the contest organizers.

      And I know that you were allowed to search the Internet.

      But submitting to the problem is another story. To me it seems like yelling straight to your (at least, Codeforces) friends that "you should read this problem", maybe this could be considered as "sharing the tasks".

      I personally clicked all the handles in the submissions list and almost all of them were Chinese accounts (there were some USA accounts, too), that's why I was concerned. My theory was that the first guy somehow found the problem and submitted, and other users who were (at least, Codeforces) friends somehow spotted it and submitted, and it spreaded all across your country? But maybe it's too much of a conspiracy theory.

      Anyway I hope there is an another comment that only blames the problem author for proposing this problem in an online contest. It seems my comment will disappear due to downvotes.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +10 Vote: I do not like it

        Sorry for my ignoring this problem before...

        And here I give a reason why I submitted this probelm.

        As the comment before says, the mirror website in China was terrible during the last two hours, so I tried using this way to check my code.

        → Reply
»
3 years ago, # |
  Vote: I like it +10 Vote: I do not like it

You can solve all problems here: https://oj.uz/problems/source/561

→ Reply
»
2 years ago, # |
  Vote: I like it -7 Vote: I do not like it

I'm waiting for yet another APIO discussion thread. Of course not open till the online round finishes. It'll be a great help to many people. Thanks in advance.

→ Reply