In the past 2 blogs, I exposed 2 suspected cheaters: [user:midoriya_,2026-05-26] and [user:batats,2026-05-26].↵
This blog is a complete summary of all the evidence and suspicious details collected so far.↵
↵
Previous blogs:↵
↵
* https://mirror.codeforces.com/blog/entry/153923↵
* https://mirror.codeforces.com/blog/entry/154029↵
↵
# 1. [user:batats,2026-05-26]↵
↵
<spoiler summary="Evidences">↵
The main reason this account became suspicious is the extremely abnormal improvement pattern.↵
↵
He registered on Codeforces around 5 years ago and stayed at newbie level for a very long time. Before the suspicious contests, his rating had never exceeded roughly 1200, and in most contests he could only solve around 2-3 easy problems.↵
↵
For example, even after years on the platform, he still performed poorly in many Div2/Div3 contests and struggled with standard implementation and greedy problems. His old submissions and contest history clearly showed a relatively weak level.↵
↵
Then suddenly, within only about 2 months, his performance changed completely.↵
↵
He jumped from around 1100 rating to over 2100 rating in only a few contests. In that period, he achieved performances that were completely inconsistent with everything previously shown on the account.↵
↵
Some suspicious points:↵
↵
* Solving 6/6 in Div2 contests shortly after struggling with basic Div3 problems.↵
* Huge rating gain in an extremely short time without gradual progression.↵
* No visible transition period between low-level and expert-level performance.↵
* Contest performances suddenly becoming far stronger than his long-term practice history suggested.↵
↵
One of the most suspicious contests was Codeforces Round 1099, where he achieved rank 2 and gained a massive amount of rating.↵
↵
Another suspicious detail is that many of the strongest performances happened in contests where multiple suspicious accounts also overperformed.↵
↵
There are also several skipped contests during the improvement period. The timeline becomes even stranger when looking at the exact sequence:↵
↵
* Weak performances for years.↵
* Several skipped contests.↵
* Suddenly returns with expert/master-level performances almost immediately.↵
↵
If someone improves naturally, there is usually evidence such as:↵
↵
* consistent upsolving,↵
* large training activity,↵
* strong gym history,↵
* active problem solving outside contests,↵
* gradual rating growth.↵
↵
But here, the jump was almost instantaneous.↵
↵
Some defenses claimed that he had strong ICPC/ECPC/EOI background experience. However, several of those claims appear misleading or exaggerated.↵
↵
For example:↵
↵
* This is reportedly his first university year, so claims about participating in many university ICPC-style competitions do not align well with the timeline.↵
* Claims about high achievements in ECPC/EOI-related contests could not be verified.↵
* ACPC Teens participation reportedly happened only once and without notable ranking.↵
↵
Another important point is the inconsistency between contest skill and general problem-solving history.↵
↵
A person who can suddenly obtain top ranks in difficult Div2 contests would normally also show:↵
↵
* strong old submissions,↵
* difficult solved problems outside contests,↵
* stable high-level performance afterward.↵
↵
Instead, the account history looks extremely inconsistent.↵
↵
There are also suspicious behavioral patterns:↵
↵
* Very sudden spikes in contest performance.↵
* Contest-only strength not reflected elsewhere.↵
* Large differences between contests close in time.↵
↵
Overall, while rapid improvement is possible, the combination of:↵
↵
* 5 years at newbie level,↵
* sudden 1000+ rating jump,↵
* rank 2 in a major round,↵
* inconsistent history,↵
* questionable explanations,↵
* and multiple suspicious contest patterns↵
↵
makes this account highly suspicious.↵
</spoiler>↵
↵
# 2. [user:midoriya_,2026-05-26]↵
↵
<spoiler summary="Evidences">↵
This account first appeared mainly to defend [user:batats,2026-05-26] in the comment section.↵
↵
However, many of the arguments were extremely weak and sometimes even made the situation more suspicious.↵
↵
Some examples:↵
↵
* Using irrelevant comparisons with genuinely talented users.↵
* Claiming that huge improvement in only a few contests is “normal” without providing convincing evidence.↵
* Ignoring the inconsistency between old and new performances.↵
* Avoiding direct responses to stronger evidence.↵
↵
After additional evidence was presented, the account became much quieter and stopped responding to several important points.↵
↵
There are also suspicious similarities between the two accounts:↵
↵
* Similar timing patterns.↵
* Similar argumentative behavior.↵
* Defending each other aggressively despite weak evidence.↵
* Suspicious overlap in contest periods.↵
↵
Another suspicious point is the attempt to dismiss evidence using obviously bad arguments instead of actually explaining the abnormal contest history.↵
↵
For example, instead of explaining:↵
↵
* how a newbie-level account suddenly became expert/master level,↵
* why there was no gradual progression,↵
* or why performances were inconsistent,↵
↵
the defense mostly relied on vague claims like:↵
↵
* “people can improve fast,”↵
* “he practiced a lot,”↵
* or comparisons to unrelated users.↵
↵
But fast improvement alone is not the issue.↵
↵
The issue is the combination of:↵
↵
* extremely long low-level history,↵
* abrupt transformation,↵
* lack of supporting practice evidence,↵
* and highly inconsistent performances.↵
</spoiler>↵
↵
# Conclusion↵
↵
Of course, only the official Codeforces anti-cheat team can make the final judgment.↵
↵
However, based on:↵
↵
* the contest history,↵
* rating graph,↵
* performance inconsistencies,↵
* suspicious timeline,↵
* weak explanations,↵
* and overall behavior,↵
↵
I believe there is more than enough evidence for serious suspicion and investigation.↵
↵
The purpose of this blog is not harassment. Competitive programming contests should remain fair for everyone who spends years practicing honestly.↵
↵
I hope that [user:MikeMirzayanov,2026-05-26] and [user:kan,2026-05-26] will hear my words and ban the cheaters mentioned above.
This blog is a complete summary of all the evidence and suspicious details collected so far.↵
↵
Previous blogs:↵
↵
* https://mirror.codeforces.com/blog/entry/153923↵
* https://mirror.codeforces.com/blog/entry/154029↵
↵
# 1. [user:batats,2026-05-26]↵
↵
<spoiler summary="Evidences">↵
The main reason this account became suspicious is the extremely abnormal improvement pattern.↵
↵
He registered on Codeforces around 5 years ago and stayed at newbie level for a very long time. Before the suspicious contests, his rating had never exceeded roughly 1200, and in most contests he could only solve around 2-3 easy problems.↵
↵
For example, even after years on the platform, he still performed poorly in many Div2/Div3 contests and struggled with standard implementation and greedy problems. His old submissions and contest history clearly showed a relatively weak level.↵
↵
Then suddenly, within only about 2 months, his performance changed completely.↵
↵
He jumped from around 1100 rating to over 2100 rating in only a few contests. In that period, he achieved performances that were completely inconsistent with everything previously shown on the account.↵
↵
Some suspicious points:↵
↵
* Solving 6/6 in Div2 contests shortly after struggling with basic Div3 problems.↵
* Huge rating gain in an extremely short time without gradual progression.↵
* No visible transition period between low-level and expert-level performance.↵
* Contest performances suddenly becoming far stronger than his long-term practice history suggested.↵
↵
One of the most suspicious contests was Codeforces Round 1099, where he achieved rank 2 and gained a massive amount of rating.↵
↵
Another suspicious detail is that many of the strongest performances happened in contests where multiple suspicious accounts also overperformed.↵
↵
There are also several skipped contests during the improvement period. The timeline becomes even stranger when looking at the exact sequence:↵
↵
* Weak performances for years.↵
* Several skipped contests.↵
* Suddenly returns with expert/master-level performances almost immediately.↵
↵
If someone improves naturally, there is usually evidence such as:↵
↵
* consistent upsolving,↵
* large training activity,↵
* strong gym history,↵
* active problem solving outside contests,↵
* gradual rating growth.↵
↵
But here, the jump was almost instantaneous.↵
↵
Some defenses claimed that he had strong ICPC/ECPC/EOI background experience. However, several of those claims appear misleading or exaggerated.↵
↵
For example:↵
↵
* This is reportedly his first university year, so claims about participating in many university ICPC-style competitions do not align well with the timeline.↵
* Claims about high achievements in ECPC/EOI-related contests could not be verified.↵
* ACPC Teens participation reportedly happened only once and without notable ranking.↵
↵
Another important point is the inconsistency between contest skill and general problem-solving history.↵
↵
A person who can suddenly obtain top ranks in difficult Div2 contests would normally also show:↵
↵
* strong old submissions,↵
* difficult solved problems outside contests,↵
* stable high-level performance afterward.↵
↵
Instead, the account history looks extremely inconsistent.↵
↵
There are also suspicious behavioral patterns:↵
↵
* Very sudden spikes in contest performance.↵
* Contest-only strength not reflected elsewhere.↵
* Large differences between contests close in time.↵
↵
Overall, while rapid improvement is possible, the combination of:↵
↵
* 5 years at newbie level,↵
* sudden 1000+ rating jump,↵
* rank 2 in a major round,↵
* inconsistent history,↵
* questionable explanations,↵
* and multiple suspicious contest patterns↵
↵
makes this account highly suspicious.↵
</spoiler>↵
↵
# 2. [user:midoriya_,2026-05-26]↵
↵
<spoiler summary="Evidences">↵
This account first appeared mainly to defend [user:batats,2026-05-26] in the comment section.↵
↵
However, many of the arguments were extremely weak and sometimes even made the situation more suspicious.↵
↵
Some examples:↵
↵
* Using irrelevant comparisons with genuinely talented users.↵
* Claiming that huge improvement in only a few contests is “normal” without providing convincing evidence.↵
* Ignoring the inconsistency between old and new performances.↵
* Avoiding direct responses to stronger evidence.↵
↵
After additional evidence was presented, the account became much quieter and stopped responding to several important points.↵
↵
There are also suspicious similarities between the two accounts:↵
↵
* Similar timing patterns.↵
* Similar argumentative behavior.↵
* Defending each other aggressively despite weak evidence.↵
* Suspicious overlap in contest periods.↵
↵
Another suspicious point is the attempt to dismiss evidence using obviously bad arguments instead of actually explaining the abnormal contest history.↵
↵
For example, instead of explaining:↵
↵
* how a newbie-level account suddenly became expert/master level,↵
* why there was no gradual progression,↵
* or why performances were inconsistent,↵
↵
the defense mostly relied on vague claims like:↵
↵
* “people can improve fast,”↵
* “he practiced a lot,”↵
* or comparisons to unrelated users.↵
↵
But fast improvement alone is not the issue.↵
↵
The issue is the combination of:↵
↵
* extremely long low-level history,↵
* abrupt transformation,↵
* lack of supporting practice evidence,↵
* and highly inconsistent performances.↵
</spoiler>↵
↵
# Conclusion↵
↵
Of course, only the official Codeforces anti-cheat team can make the final judgment.↵
↵
However, based on:↵
↵
* the contest history,↵
* rating graph,↵
* performance inconsistencies,↵
* suspicious timeline,↵
* weak explanations,↵
* and overall behavior,↵
↵
I believe there is more than enough evidence for serious suspicion and investigation.↵
↵
The purpose of this blog is not harassment. Competitive programming contests should remain fair for everyone who spends years practicing honestly.↵
↵
I hope that [user:MikeMirzayanov,2026-05-26] and [user:kan,2026-05-26] will hear my words and ban the cheaters mentioned above.
