Hello Codeforces,
I have just been practicing during final hour of the open-hacking phase of yesterday's Div. 4 round, when I noticed that someone has just successfully hacked his/her own solution submitted during the contest!
Is there any reasonable explanation for doing that?
Why not you tell me that first
I am just curious to know if there is any plausible motivation.
let say if there is a algorithm that runs in O(log4/3(n)*e^nlog3.53(n^5/3.4)/log4(log(log(n*n-3)+n^(4+n))) and then you eventually find it. So all you now want to do is hack yourself. Good day to you.
Thanks for the kind correpondence. I am not sure about the benefit of hacking my own solution. Suppose that I find an algorithm with lower complexity, why don't I just make new submission instead of using the hack option? Is there any benefit to invalidating my own solution during the open-hacking phase? Let me ask you the question in other words. Suppose that the solution is not hacked, and that it failed to pass the system test. Which situation is better for me? Isn't there any chance that the solution with the higher complexity which passed the pretest would have passed the system test?
It's probably to add your test to system tests.
Very simple example.
Question : Given 3 numbers less than $$$10^9$$$, output their sum.
Your Code
This code is wrong because of overflow. But many participants may make this mistake. So if they get WA on system tests, your rank will be better. So if you want to add a testcase where the numbers will overflow, you can submit this, and then hack it. Obviously the pretests won't be that bad, but that's the general idea.
Ok. But then, the contestant would have lost his/her own submission by self-hacking. How would that improve the contestant rank?
I think the reward from the hack can sometimes be better than the points of the problem .
Well, it depends, but I'm inclined to say that the user found a counterexample for the submission, and hacked himself
In this particular contest: I used a small script to filter only the successful self-challenges
There are 9 challenges done during the open hacking phase (19:35 to 7:35, UTC+3. Because of a Codeforces bug/unimplemented feature, time on /hacks page is always displayed in UTC+3):
lol why have you created a new account to comment this
Why not? I don't spam anyway.
That's not an argument
Because it's better than being hacked by others. also it's useful to train spotting mistakes.