21.0's blog

Test cases for problem D in the last contest (CF Edu Round 173) aren’t good enough
By 21.0, history, 12 hours ago, In English

In the last contest 4th problem was a bit wired and participants should determine how many iterations are enough to solve the problem and not exceeding the time limit, in the hacking phase some solutions hacked which passed all the test cases for example i submitted the same code that was hacked after final standing released this code during the contest get hacked and after the contest was accepted.

-my submission that was hacked: https://mirror.codeforces.com/contest/2043/submission/298290829

-my submission that was accepted: https://mirror.codeforces.com/contest/2043/submission/298322049

so there are still many lucky participants that their solutions wasn’t correct but they didn’t fail in the test cases please do something about this AcidWrongGod, BledDest and Ferume.

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12 hours ago, # |
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Auto comment: topic has been updated by 21.0 (previous revision, new revision, compare).

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10 hours ago, # |
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all the solutions will be rejudged in the upcoming system testing, dont worry lol

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    10 hours ago, # ^ |
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    I thought system testing is done

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      10 hours ago, # ^ |
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      its gonna start in some time ig, but it hasnt been done yet

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        9 hours ago, # ^ |
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        No its already been over for a couple hours now, it says Final standings in the contest.

        UPD: Unless I'm wrong and thought it should say "Pending system testing"

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          9 hours ago, # ^ |
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          have u seen system testing happening?, because im pretty sure that it shows "final standings" even before system testing for educational/div3/div4 rounds

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            9 hours ago, # ^ |
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            Look at the previous EDU round, it already has rating change and still says "Final standings, open hacking phase finished". Same thing.

            UPD: Nevermind I'm probably wrong, my contest submission's Sent === Judged time so no system testing yet. They should change it from "Final standings" though. It's very misleading.

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6 hours ago, # |
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I hope the editorial will contain a formal proof on how many iterations it should take. I have seen that submissions(after the contest) have passed the testcases on just running for the first 100 numbers from l/g on the outer loop and am confused as to what should be the actual upperlimit.

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    3 hours ago, # ^ |
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    I really don't know why they choose the weakest test cases for the pretests this contest pretests was extremely stupid, over many hundreds of hacks and system test failures happened There were so many, it wasn't normal. It was really awful the one who set the pretests owe an apology to every participants.

    AcidWrongGod BledDest Ferume

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    3 hours ago, # ^ |
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    I saw a comment that said you only have to check the ranges $$$l, l + 5$$$ and $$$r - 5, r$$$. At least one of them will have a $$$\gcd$$$ equal to $$$1$$$. During the hacking phase, I tried pretty hard to find a counterexample, but I couldn't.

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