Today, I want to expose _Cinder, a user who recently reached the Master rank. After looking through his recent contests and submissions, I strongly believe that this account is cheating.
The account was an Expert with a rating of around 1600 in December 2025. After a break of about 1.5 years, the user suddenly returned and gained nearly 600 rating points within only three contests, reaching Master (2176). Such an improvement alone is not proof, but the submissions themselves are much more concerning.
The most recent contest was Order Capital Round 2, where the user solved seven problems. The coding style changes dramatically from one problem to another. In problems B, C, E, and G, the variable names are relatively short and simple. In problem D, underscores suddenly appear everywhere. In problem F, the code starts with one style and later switches to another style with many underscore-heavy variable names and additional helper functions. It looks as if two different people wrote different parts of the code.
The same thing happened in Educational Codeforces Round 191. Problems A through E1 use a fairly consistent template and coding style. However, the last submission for E2 is completely different. New helper functions suddenly appear, variable names become much longer, and the overall structure no longer resembles the earlier submissions. Such drastic changes within a single contest are highly suspicious.
The first contest after the user's return, Codeforces Round 1102, is even more concerning. The submissions contain extremely long variable names filled with underscores, a style that appears repeatedly in AI-generated code. Comparing these submissions with the user's previous coding style makes the difference very obvious.
Of course, any single piece of evidence may be explained away. However, when we combine the sudden 600-point rating increase, the six-month break, and the repeated changes in coding style both across and within contests, the conclusion becomes difficult to ignore.
In my opinion, this account is cheating. I hope the Codeforces administrators review these submissions carefully. If anyone disagrees, please explain why in the comments.
Note : underscore = '_'
Hope _Cinder won't use useless excuses anymore.
LOL, the long variable names with “_” were simply Vietnamese names, because I thought I had enough time to write my code carefully. In later contests, I shortened them to save more time, though it is still a hard habit to break. Using “_” instead of spaces in Python variable names is completely normal, you are only overreacting. And Codeforces is not the only platform for practicing competitive programming either, so watch your words.
Getting top 20 and getting LGM perf in a div1 is crazy impressive tho, that's why people are suspicious about you, personally i have no idea whether you cheated or not, if you didn't then congrats.
Where have I read this before?
Anyway you can easily prove this, just send the links of your profiles on these other platforms you talk about, that's if they prove a thing, because if they do you would have put them in your comment before commenting.
What about this submission? While debugging with only a little time left, you somehow decided that "I still have enough time to carefully rewrite my code" rather than "I should fix the bug as quickly as possible to get AC." You changed the entire template, switched your variable-naming style, and rewrote parts of the code that were unrelated to the bug.
Furthermore, your previous submissions consistently used
tsas the variable for the number of test cases, but here you suddenly changed it totfor no apparent reason. You also renamed variables that serve the same purpose, such as changingLtok.These changes do not look like the kind of edits someone would normally make while rushing to debug a solution during a contest.
_Cinder
So I wrote it in the most readable, even if longest, way possible just to figure out where it went wrong. Why didn’t you consider that I simply wanted to get AC? If I wanted to cheat, I could’ve used the old code and asked AI to debug it for me. To clarify, I hadn’t even bothered doing problems on this platform for 1.5 years. That time in December 2025 was just me teaching some juniors how to code.
Then how do you explain the variable changes?
detective work
L core
The Vietnamese variable names aren't what raised eyebrows.
What's odd is the complete discontinuity.
Before the six-month break, your submissions look exactly like what you'd expect from a ~1400-rated account. Short variable names. Straightforward code. Multiple wrong attempts on problems like Watermelon 4A - Watermelon and Theatre Square 1A - Theatre Square, two of the most beginner-friendly problems on Codeforces. These were dated 4rth September, 2025. 336820463
Then you disappear for six months.
You come back with an entirely different coding style. Suddenly every variable is semantically named, recursive lambdas appear, the code becomes unusually verbose, and your contest performance jumps from ~1700 to Candidate Master in three rated contests. The latest (div1 + div2) contest had a 3025 performance.
There's another curious detail. Your second accepted submission on the account is a 2300-rated problem. Your third accepted submission is an 800-rated problem. Both took roughly 10–12 minutes.
None of these observations prove AI.
But "the variables are Vietnamese" doesn't address any of them.
The question isn't whether Vietnamese programmers use underscores.
The question is why the person writing the code before the break and the person writing the code after the break look like two completely different programmers. _Cinder
That is 1.5 year
I don't think that you're a cheater! But let's check your accounts at other CP websites! No harm!
Well for 722F, the submission already used inline functions, so they could have just changed their coding style from inline to a normal one
Those variables are longer, but they are easier to understand, and this submission does have long variable names, I have seen other people do that. But I feel like this is a bit suspicious,
Idk, it is suspicious, but not entirely cheating
The style has already appeared in problem A, and I don't think people use AI on A, so it might be that they have changed their coding style
One of the people I know did this, they practice using short variable names, but the next day, they decide to use long variable names
First, it is a 1.5 year break, you could learn a lot from that time, as I said, I explained the changes in the coding style
In conclusion, this person might be cheating, but the evidence you gave is not enough
That still doesn't explain why _Cinder would drastically change their coding style right in the middle of Educational Codeforces Round 191.
Why can't _Cinder use AI all over the contest?
Please don't defend with nonsense argument.
I mean I saw a person change their coding style over-night, Cinder didn't change the style mid-contest, it was from the beginning, and I think Cinder wouldn't use AI for problem A (because you are saying A looks like AI) since they were already near expert before they left, so that style is consistent with the contest, I think Cinder is not cheating :). Also, why would anyone use AI over ALL contest? It just takes out the fun of doing it.
I am not Cinder so I can explain all the questions, it is just my predictions.
He did. Submission.
Can't understand why you defend for a cheater.
To me, Cinder is not a cheater, so I defend them
son, he is clearly a cheater(see the blog above if you have eyes)
After some investigations, I found out that you've 1 skipped contest: Codeforces Round 1054 (Div. 3). How are you explaining this?
Mitpro
looks like we will have a new blogs about a new cheaters...
a new blogs? a new cheaters?
cant understand why people downvote this comment. He just said the truth.
pls upvote me and downvote wrusb
Did I say anything wrong?
why downvote me?
why upvote you?
mike please ban this guy
how about you?
Nice profile photo btw
Sir, it's very easy for you to prove your skill. Just send us your other CP platforms account so that we can see how you improved in 1.5 years!
Hello ! It’s good to see so many vigilantes on codeforces platform . I am sure you have the capacity and skills to judge others . Only if you focus on your own performance, you all would have improved your skills and ratings too .
Edit — this message should have been polite not satirical. I regret taking this tone .
When that other is that obvious it no longer requires skill
Also thanks for showing yourself, you would have gone under the radar without writing this comment, now we are back to the classic case of apes (cheaters) together strong
You only participated in a single contest, in that contest you obviously cheated, a lot of wrong answers on test 1, you either are mentally disabled or a cheater who is even too lazy to run their code
Nothing you say will explain how these two submissions are two minutes apart
Furthermore it's obvious that these two submissions are AI generated from the coding style and names
Even more you switching templates between these two problems make you much more suspicious
What you did is clearly assign that you don't focus on your performance, you are just another braindead cheater who is too coward to use their main account because they know they will be caught.
You solved few very interesting problems .My point is leave this vigilante work for administrators. You focus on your own learning . I wish you all the best . Let codeforces be the shining star for all those who want to learn and grow
For all those dishonest cheaters who got here by cheating—we're here because we genuinely want to excel in competitive programming. Some of us are aiming for the IOI, ICPC, or preparing for software engineering jobs. We don't need fake motivation or shortcuts. I honestly wonder what those cheaters will accomplish in life. Cheating may bring temporary success, but it earns no respect.