I am writing to document a pattern of behavior by the user tuanha that I believe merits careful review. My intention is not to make accusations beyond the available evidence, but rather to present observations that I believe are sufficiently unusual to justify an independent investigation by the Codeforces team.
The primary concerns include:
A pattern of contest performance that appears inconsistent with prior history. Statistical indicators that, in my view, are unusual enough to warrant further examination. Additional observations that I have collected and can provide upon request, including supporting graphs and contest data.
I understand that none of these observations alone prove misconduct. I also recognize that exceptional improvement is possible through legitimate effort. For that reason, I respectfully ask that the administration evaluate the available evidence using whatever internal tools, logs, and information are available to you.
I would also like to mention that I currently live in Albania. I include this only because I would appreciate that any investigation be handled confidentially and that my identity not be unnecessarily disclosed. I have no desire for public conflict and simply wish to report what I believe should be reviewed.
Thank you for your time and for your continued efforts to maintain the integrity of Codeforces competitions.
Thanks for making the post. I too find this user suspicious. Just the fact that every submission has time + space complexity written in the top of the code, as well as listing the main ideas — it's a very unusual thing to do.
Not to disregard the possible pronouns of the person, but every comment says "we" who are "we" ? It gives off a strong AI smell...
Further evidence: The “tuanha” account is also registered on AtCoder with a rating of ~100. tuanha's first contest on Codeforces was in July 2021, and their first contest on AtCoder was also in July 2021.
The explanation for Problem A in their own code is longer than the explanation for Problem F. Also, Problem B, which has a fairly long explanation plus code, was solved in 3 minutes.
Why has Codeforces been ignoring participants like this for so long? It seems impossible to me to go from solving Problem A in 34 minutes to GM-level performance in just one year. Maybe it’s just my skill issue, but even this account’s rating graph looks super suspicious.