After reading MikeMirzayanov's blog, I decided to investigate TimDee again and found even more accounts than I expected. (Previous blog about this issue)

Accounts that are likely his:

TimDee, TimaDegt, definitelynottimdee, IHatePaiu, AlinLoh420, RobertLoh420.

Some of these were created after the previous blog and participated in many contests, meaning he didn't feel any remorse.

Offenses I found (ordered by date):

Codeforces Round 890 (Div. 2) supported by Constructor Institute, (TimaDegt)

This is likely a case of multiple people using one account. Looking at the submission times and the codes (especially headers) reveals that while submissions for problems D {217324769} and E1 {217299337} were written by TimaDegt, submissions for problems A {217296384}, B {217302862}, C {217292141}, and E2 {217351566} were likely written by prvocislo. Even though the account was participating out-of-contest, I think it should still abide by the rules (if there is a rule that allows this, please let me know).

Codeforces Round 875 (Div. 2), (IHatePaiu)

Here, IHatePaiu ranked 3rd in the contest, which likely affected many participants.

The fact that he submitted the same codes after the contest shows that it is his account.

{207716387}, {207771011}, and {207622747} are the same.

{207716972} and {207658220} are the same.

Codeforces Round 812 (Div. 2), (TimDee, IHatePaiu)

Codeforces Round 797 (Div. 3), (TimDee, IHatePaiu)

Codeforces Round 791 (Div. 2), (TimDee, IHatePaiu)

Codeforces Global Round 20, (TimDee, IHatePaiu)

I hope this will help Codeforces design a system to detect people using multiple accounts. It seems like doing plagiarism testing on skipped submissions and adding a phone verification method could be useful.

I apologize for any errors I could have made. If you have any suggestions or objections, feel free to write them in the comments. Additionally, if you would like to report a difficult cheating case or would like to help with exposing cheaters, feel free to DM me.

I was looking at the standings of CodeTON Round 6 (Div. 1 + Div. 2, Rated, Prizes!), and I noticed this person submitted problems in reverse order and very fast, which made me very suspicious.

I investigated more and found out that he had one more account that also participated in the contest.

It was obvious they were the accounts of the same person because they had similar names and organizations and used exactly the same template in the past.

Then I started looking at the codes.

It was obvious that the codes submitted by TimaDegt were changed versions of the codes submitted by TimDee. He wanted to escape the plagiarism detector, and he was successful because his account didn't get skipped. However, the similarities are obvious. The codes of TimaDegt use the same defines and coding habits, like whitespaces and newlines.

However, this isn't a good enough proof. If it weren't for a mistake he made, he would've gotten away with it.

• 223858049
• 223857848

He submitted exactly the same code from both accounts, which proves he used both accounts in the contest.

I looked at other contests and found many more contests where he also used both accounts. They're also full of many "coincidences".

• Codeforces Round 867 (Div. 3)
• Codeforces Round 855 (Div. 3)
• Codeforces Round 853 (Div. 2)
• Codeforces Round 851 (Div. 2)
• Codeforces Round 843 (Div. 2)
• Educational Codeforces Round 141 (Rated for Div. 2)
• Codeforces Round 842 (Div. 2)
• Codeforces Round 841 (Div. 2) and Divide by Zero 2022
• Codeforces Round 850 (Div. 2, based on VK Cup 2022 - Final Round) Codeforces Round 850 (Div. 1, based on VK Cup 2022 - Final Round)

People wouldn't expect a high-rated person to cheat, but he did. He's also a medalist from IOI 2023 (Timur Degteari), which only makes things worse. I hope the 2 TON he earned from cheating was worth ruining his reputation. I also hope that Codeforces gets better at cheater detection.