H3X460N157's blog

Educational 136 hacks
By H3X460N157, history, 8 months ago, In English

After CF Educational 136 about 4000 solutions were hacked in two hours. What the hell is that? Could anyone explain, how it's possible? Is the problem with 4000 solutions or with the system testing?

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8 months ago, # |
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Auto comment: topic has been updated by H3X460N157 (previous revision, new revision, compare).

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8 months ago, # |
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When you have hacks part in contest tests in problems usually weak. That’s why a lot wrong solves were accepted. This is because hacks part, if tests will be strong then you wouldn’t has ability to hack

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8 months ago, # |
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Testers suck really hard

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8 months ago, # |
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tests were weak + alot of people in problem B were hacked due to a simple mistake since the diffrence between the previous sum and current element in array d should be >= 0 and d[i] != 0 then ans = -1 because basically if this happened you can use in this index in answer two diffrent elements which will make the answer not unique but most did it > 0 so basically case 2 6 8 for example they will fail because 2+6 = 8 and 8-8 = 0 and ans should be equal -1. i used this test to hack 14 people.

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    8 months ago, # ^ |
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    I agree. I was hacked too due to this. I regret it lol

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