Square__Head's blog

By Square__Head, history, 9 months ago, In English

Problem E1 from the latest Div2 was already used before in a different contest. It's the same as 1486D - Max Median

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9 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

This isn't a rare occurrence and also not usually a big deal unless the author copied an existing problem intentionally, which is obviously not the case here.

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    9 months ago, hide # ^ |
     
    Vote: I like it -11 Vote: I do not like it

    It's just not fair tbh, I don't mean like a similar idea was used before—I mean it's literally the same problem, just worded differently it is like leaking probs

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      9 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      It's not the same problem, they have different definitions of a median

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        9 months ago, hide # ^ |
         
        Vote: I like it -10 Vote: I do not like it

        ok they are not copy-paste prob XD

        but still anyone with rate > 1000 can edit the code to get it accepted in this version

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          9 months ago, hide # ^ |
           
          Vote: I like it +7 Vote: I do not like it

          We are very sorry this happened. We didn't know about this problem (although I did solve the problem lol).

          See here for an explanation. Btw, I just want to point out that it requires a little insight: maximal submedian (with our definition of a median) = maximal submedian (with the usual definition of a median).

          I do not think it is that trivial, but apparently it is.

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      9 months ago, hide # ^ |
       
      Vote: I like it +4 Vote: I do not like it

      If we unrate a contest every time a problem is a duplicate or subproblem of an existing problem, we would be unrating at least half of all contests (and nearly all Div. 3 and Div. 4).

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        9 months ago, hide # ^ |
         
        Vote: I like it +1 Vote: I do not like it

        I'm not saying the round should be made unrated, but I do think the author should check if the problem was already used before or not

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          9 months ago, hide # ^ |
           
          Vote: I like it +14 Vote: I do not like it

          They probably did check, and just didn’t find this problem. You can’t expect a team of coordinators, problemsetters, and testers to know every single CP problem that has ever been set before.

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            9 months ago, hide # ^ |
             
            Vote: I like it -9 Vote: I do not like it

            Tester: we didn't know about test 5.

            Setter: we didn't know about problems.

            So they are a bad coordinators LOL, just search or ask.

            square head found the problem and the setter didn't, is square head better than the setter!

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              9 months ago, hide # ^ |
              Rev. 2  
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              1/10 rage bait

              You are free to try to write your own contest if you think it is so easy to write one without any issues

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                9 months ago, hide # ^ |
                 
                Vote: I like it 0 Vote: I do not like it

                I did a lot man, this is my alt because I know that I will be downvoted

                I'm not a master and can't make a masters problems so I can't make a division

                If the setting is not easy then getting WA in system test is not easy also

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            9 months ago, hide # ^ |
            Rev. 2  
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            did you read the prob ? it actually the same basic search on google will get you the prob just search "max med for range l ,r on CF" and you will see it as first link

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9 months ago, hide # |
Rev. 4  
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Everyone can use this to check whether the problem is used before

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9 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

Sorry about that. E2 (hard) was invented first and the subtask E1 was added later to balance the difficulty, so this was clearly not intentional. Nobody (authors and testers) realized this problem already existed. You can read more about problem coincidences here.

Some people have pointed out that http://yuantiji.ac could be used. I think it's best to avoid external services to avoid problem leakage, but it could be cool if Codeforces had a self-hosted version of that.