Title: Cheating Report: Account nvhoang in AtCoder Beginner Contest 479↵
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Hello everyone,↵
Note: Since my English is not very good, this blog post was translated and polished with the help of AI.)↵
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Following up on my [previous post](https://codeforces.me/blog/entry/157523) regarding account [nvhoang](https://atcoder.jp/users/nvhoang) ([user:NGUYENVUHOANG,2026-10-11]), he has once again exhibited clear signs of cheating in AtCoder Beginner Contest 479 — in fact, I am completely certain of it. After several cheaters were removed from the official standings, his rank jumped straight into the Top 5.↵
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To verify my suspicions, I prompted Claude (Sonnet 3.5) to solve problems F and G. To my surprise, the core logic, algorithmic approach, and code structure generated by the AI were almost identical to his submitted solutions, with only minor tweaks made to disguise the AI footprint. ↵
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Anyone can easily verify this by generating a solution using Claude/ChatGPT for problems F and G and comparing the output directly against his submissions [here](https://atcoder.jp/contests/abc479/submissions?f.Task=&f.LanguageName=&f.Status=&f.User=nvhoang)↵
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Furthermore, it appears he has become aware of anti-cheat detection: he seems to deliberately stall and delay his submissions to avoid triggering automated flags for suspiciously fast solve times.↵
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I urge the AtCoder admins and community to inspect his submission history for ABC 479 and take necessary action.↵
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[user:atcoder_official,2026-10-11] read this please.↵
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↵
Hello everyone,↵
Note: Since my English is not very good, this blog post was translated and polished with the help of AI.)↵
↵
Following up on my [previous post](https://codeforces.me/blog/entry/157523) regarding account [nvhoang](https://atcoder.jp/users/nvhoang) ([user:NGUYENVUHOANG,2026-10-11]), he has once again exhibited clear signs of cheating in AtCoder Beginner Contest 479 — in fact, I am completely certain of it. After several cheaters were removed from the official standings, his rank jumped straight into the Top 5.↵
↵
To verify my suspicions, I prompted Claude (Sonnet 3.5) to solve problems F and G. To my surprise, the core logic, algorithmic approach, and code structure generated by the AI were almost identical to his submitted solutions, with only minor tweaks made to disguise the AI footprint. ↵
↵
Anyone can easily verify this by generating a solution using Claude/ChatGPT for problems F and G and comparing the output directly against his submissions [here](https://atcoder.jp/contests/abc479/submissions?f.Task=&f.LanguageName=&f.Status=&f.User=nvhoang)↵
↵
↵
Furthermore, it appears he has become aware of anti-cheat detection: he seems to deliberately stall and delay his submissions to avoid triggering automated flags for suspiciously fast solve times.↵
↵
I urge the AtCoder admins and community to inspect his submission history for ABC 479 and take necessary action.↵
↵
[user:atcoder_official,2026-10-11] read this please.↵
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