ZCKevin's blog

Something about oj.uz
By ZCKevin, history, 3 years ago, In English

Recently I tried to upsolve this problem

In the problem statement, subtask 5, 6 should be independent scored from subtask 1, 2, 3, 4

However, subtask 6 is linked with 1, 2, 3, 4.

which means if I failed subtask 1, I cannot get my normal scoring on subtask 6.

When I tried to score only on subtask 6, I always get unknown WA.

I wasted so much time debugging, while the problem was not on me.

I wanted to report this issue to oj.uz, but I couldn't find a way to do so.

Does anyone know how to report this to oj.uz ? so that if something similar happen next time, There's a way to fix it.

Thanks!

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3 years ago, # |
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Auto comment: topic has been updated by ZCKevin (previous revision, new revision, compare).

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3 years ago, # |
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I think you can tag ojuz

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

Someone's training for IOI (づ｡◕‿‿◕｡)づ

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    3 years ago, # ^ |
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    I was beaten badly by IOI 18 day2 QQ

    I had a full score idea for pA in my last 40 minutes. but due to some small error, my solution required a bit more than expected

    but getting WA instead of partial score made me believe that there's something WRONG about my code rather some small constant factor.

    I found that subtask linking issue after I tested it locally with IOI official testcases. QQ

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

      Same. I thought it was an error from my code. But after revising my code multiple times and testing it on large testcases, I concluded that it was error from oj.uz. Because basically, my code gets score with same code in M=1 subtask(subtask 5). And an upgrade from subtask 5 to subtask 6 in my code is literally just 1 line of code.

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        3 years ago, # ^ |
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        it felt terrible during a virtual, cause that should never happen during a formal contest.

        (Though in Taiwan training camp, there was once a big mistake in test cases.

        And it was found out after the training camp ended ......)

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3 years ago, # |
← Rev. 2   Vote: I like it +23 Vote: I do not like it

Sorry for that, I mistakenly thought in every IOI 2018 problem the last subtask should contain all the other subtasks.

Now it's fixed, but I'm not sure whether re-grading all the submissions is possible since it would take too much time.

To contact me, you can send me (ojuz) PM, or click the green button on the lower-right corner of the website.

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

Not only this, but it turned out the whole score scheme was wrong (so completely wrong that I can't describe it in words).

So, there's no choice but to re-grade all the submissions. Thanks for reporting this issue.

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