Hello, last night I checked the final standings of the 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 checked every other recent contests but he never used Java in any other contest. 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 in 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 comments 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 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.
Auto comment: topic has been updated by thanglieu (previous revision, new revision, compare).
no way!!
absolute cinema
I think it is NOT ONLY a personal thing (like to ban the cheater's score), but also a bitter lesson. Because of this, we cannot know if our rankings is actually shown in a fair way. And this also shows the anti cheating system of codeforces is not strong enough.
Sadly, anti cheating will never be strong enough cause AI is advancing very fast.
I couldn't agree more. As the Chinese saying goes, "As virtue rises one foot, vice rises ten.(道高一尺，魔高一丈)" This reflects how the fight against cheating is a perpetual cat-and-mouse game: however fast anti-cheat technology advances, ways to bypass it keep pace, leaving the best protections vulnerable.
toberu roasted a possible cheater in one of his blogs. Who wouldve thought he is also a cheater lol
Game recognize game
nahhh T.T
This sounds like a proof by lack of imagination. "I see something I find suspicious, I see one interpretation that fits my narrative, I'm not gonna look for more". I hope you guys are more rigorous in your mathematical proofs than this.
If the poor guy switched from C++ to Java, I think, he deserves our compassion. Could be a genuine attempt to quit a terrible language, which this time, unfortunately, ended with going for a language that is as bad, but in its own unique way. Let's show some support and hope that he tries Haskell or Rust next time.
"to quit a terrible language"
This blog post feels like reads like a witch hunt to me. It's completly reasonable for someone to try to learn a new language. It's also completly reasonable for them to add comments to help them remember unfamiliar methods by comparing them to ones you are familiar with. Deleting comments is a bit strange but I've done it before to have a shorter final code as well.
what actually happened was even more silly btw
Competitive programming is meant to be fun. The time spent digging into these issues could have been better used on your own problem-solving. Calling out people like this feels like a waste of effort.
Yeah, in Codeforces cheater database (https://cf-cheater-database.vercel.app/) from an official admin of Codeforces (repo here: https://github.com/macaquedev/cf-cheater-highlighter) has his username. He cheated once
Congrats lil bro for somehow gapping the IOI'er in VNOI cup. I hope I will see your name in the top 32 VOI (the very first qualification round in our country for those who don't know) next year