I got this message today from system:
Attention! Your solution 295598611 for the problem 2040C significantly coincides with solutions fbrunodr/295598611, gunjackk28/295637944. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://codeforces.me/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.
I use my personal laptop to code (so this is not unintentional leakage) and haven't provided my source code to anyone. The only thing I can think of is that someone abused the hacking feature of codeforces to leak my source code to a friend (as leaking their own source code would be to obvious, right?). The user who copied my code is gunjackk28 from India. He submitted the problem in the very last minute of the contest (01:59:05). Checking my room in the contest, only 3 other people got AC on the copied problem (problem C); one of them, HardikChoudhary, is also from India and got AC at (01:55:53), just 3 minutes before gunjackk28 submitted an exact copy of my source code. I think this is highly suspicious and should be investigated.
I never violated a single rule in codeforces and now I am being threatened to be blocked/banned because someone else cheated, this is completely unfair. I think the best solution in this case would be to remove the hacking during contest feature, as has already been suggested in another post.
Just before someone suggests it might be a coincidence, it is impossible in this case, as I use a highly specific .cpp file as template (which can be found in my GitHub). You can check the submissions here and see that there is no explanation other than the guy simply copied my source code:
My submission: https://codeforces.me/contest/2040/submission/295598611
gunjackk28 submission: https://codeforces.me/contest/2040/submission/295637944
Edit. 1: As some people have commented in this thread, it is impossible for HardikChoudhary to have leaked my code, as he did not lock problem C. That said I have no idea how this could have happened. I have already changed my password on Codeforces and I will just pray this won't repeat. I don't have any extensions set on my browser and all the extensions on my VScode are safe (either from Microsoft or with 1M+ downloads).
Edit. 2: This is especially disheartening was this was the first contest done on my new laptop (M3 MacBook) :(
You can only view other solutions and hack them, if you lock a problem. Neither the person you accused nor anyone else in your room has locked problem C. Therefore it is not possible that your solution was leaked through the abuse of hacking.
I agree that the submissions are too similar to be a coincidence, so there must some other way your code was leaked.
Can someone from another room see my solution if they lock the problem?
No. The only way to abuse the hacking system is to be high rated and solve a hard problem, lock it, and then steal the solutions from other high rated people who locked it as well and then share them. If nobody in your room locked it, then that means this could not have happened.
Did you use an online IDE?
No, I only used vscode on my laptop
Nobody locked in C in your room, so we can count that out. Assuming you didn't cheat(which i am inclined to believe, as you actually do use the template and also seem like a legit guy), then it must be some form of unintentional leakage, but my only idea was a public online IDE, and now im pretty confused.
I just checked my extensions in vscode and I saw nothing suspicious. I use safari and I have no extensions. Either someone with admin power leaked my source code or someone logged into my account. I checked my email and nobody other than myself logged into my account recently (although it may still be the case that someone long ago logged into my account and haven't used it until this moment). I will update my password and just pray that this never happens again, as I have no idea how this could have leaked.
Same happened to someone I know, he was a cheater though(quite obvious when looked at his earlier codes, he cheated quite often earlier) so he deserves to be banned, but you do seem legit, no one will cheat for the 1st time after getting to CM. Maybe some high rated user just felt like targeting you :)
wait a minute i didnt cheat anything... i am just seeing this blog and saw my rating is dropped and my ranking is dropped to 12k ...? i didnt solve c in that contest neither submitted how am i facing this allegation i do cf for fun i cant solve a 1600 rated problem as of now. This has happened to me fore also due to which rank was dropped to 10k.. I though this used to happen bcuz plag checkers takes account of code similarity of >95% something like that... Another proof is that i use a specefic template for my code which indeed i copied from someone but i dont think that is cheating??? if so i will stop it and coming to point that template is not on that submission of mine and then how is this possible?