sus cheater found on Codeforces Global Round 31 (Div. 1 + Div. 2)

Revision en1, by thanglieu, 2025-12-24 20:42:08

Hello, last night I checked the final standings at contest Codeforces Global Round 31 (Div. 1 + Div. 2) and found something unusual. This guy (aka toberu) had really suspicious behaviour on that contest.

He reached GM with rank 69, that's totally legit, right?

Okay I was just kidding.

Firstly, in this contest he used only Java. It is really normal until I check every other recent contests but NO contest he used Java. Do you see something unnatural? Why does he change the language on this contest? Is there anything suspicious behind this?

Secondly, this is the first submission of toberu at this contest (354179748).

Do you see this? Why does he comment at this code? Something like "__builtin_clzll(d) is equivalent to Long.numberOfLeadingZeros(d)". If you don't know, __builtin_clzll() is a C++ function, and with this comment, I have a doubt that this guy has used AI to convert C++ code to Java.

And this is the comparision between 354179748 (1st submission) and 354180518 (2nd submission)

Why does he even try to remove comment at the 2nd submission? It makes sense that he was trying to not be reported. But the first submission is enough to prove that he was cheating.

This leads to only one thing: He was cheated by some reason using C++, the he used AI to convert every code to Java to avoid MOSS. I think he should be aborted on this contest.

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  Rev. Lang. By When Δ Comment
en5 English thanglieu 2025-12-24 20:53:38 0 (published)
en4 English thanglieu 2025-12-24 20:52:47 241
en3 English thanglieu 2025-12-24 20:52:21 284
en2 English thanglieu 2025-12-24 20:43:06 216
en1 English thanglieu 2025-12-24 20:42:08 1710 Initial revision (saved to drafts)