Блог пользователя F202130100

Автор F202130100, история, 10 лет назад, По-английски

Hello Codeforcers!!

What do you think about Pretests?? Is it better that Pretests will be weak?

In a normal programming contest there is no Hacks and pretest but in codeforces weak pretests are a technique for Authors to make Problems have lower accepted solutions But maybe Hacks make contests more attractive and... .

Please write your comment about Pretest and so write your reasons. Tnks a lot.

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10 лет назад, скрыть # |
 
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I think, if there are small number of tes cases, system will work fastly during contests, so they find this pretest idea and added nice thing — hacks..

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10 лет назад, скрыть # |
 
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Weak pretests are good only for tasks with small code because when the expected code is big the probability of bug is bigger so you need to know is you code correct or not at least for 50-80 %.

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10 лет назад, скрыть # |
 
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Pretests is the reason ratings drop for most people, even after they've correctly identified the main idea. This makes us strive for accuracy from a blind spot.

Pretests adds extra difficulty to the contest, so once you get familiar with a pretests type contest, you find it easier to tackle contests like FHC, GCJ, where accuracy matters a lot, and by extension all other contests.

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10 лет назад, скрыть # |
Rev. 2  
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They suck a lot when they are too weak (the winner becomes the hacker with the most fails in his room).

They suck a lot when they are not weak but they don't include a special very silly test case (a test that could be fixed by just adding on "if", change default answer from -1 to 1, or such thing) because when you fail the System Test you get a low rank while you clearly deserve a much better rank. At least give us some points to get a better rank than someone who solved 3 problems and quit the contest!

Conclusion: they suck anyway.

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10 лет назад, скрыть # |
 
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I always believe that pretests should time out naive solutions. If N = 10^5..pretests should not allow 0(N^2)..because seriously that's like giving free 100 points to anyone in his room.

Pretests should also be strong enough to make "very non correct" solutions fail. Even though we cannot really "define" very non correct, sometimes there is a greedy solution but it's very obvious that is wrong, then pretests should fail that one, because otherwise 100 easy points. If it takes you time to think however, then maybe it shouldn't.

Hacking should be rewarded for those who can truly trace a code, and that's how it improves your debugging ability. Timing out a very naive solution or hacking very obvious wrong greedy is not an "art".

Some can argue that "at least he tried to hack a solution", but since rooms are random, that means luck really decides who gets easy hacks.

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10 лет назад, скрыть # |
 
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I personally like having pretests, it improves the ability of writing a bug-free code from the first time. And of course the great feeling of hacking someone who locked his solution :P

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9 лет назад, скрыть # |
 
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The pretests were so bad in the last few contests in CF that I don't think they should be included...I mean some solutions that pass the pretests ARE SO VERY WRONG...sometimes contestants solve completely different problems and they pass the pretest...CF should make the pretests better or exclude them at all cuz almost any solution is getting AC during the contest...

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9 лет назад, скрыть # |
Rev. 3  
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In my opinion, there are two completely different cases.

If we are speaking about common CF round, it's just a training. So, here pretests is a really nice idea because it forces participants to improve their coding accuracy and their code-reading and debugging skills, which is extremely useful in official competition like ACM etc.

But I strongly believe that it's a big mistake to spread it on official contests. This system becomes really unfair if we are speaking about competition where there are real prizes. Can you imagine IOI or ACM with hacks? I think it would be a disaster.

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9 лет назад, скрыть # |
 
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pretests are pieces of shit :)