Hello, in this post I will describe what I believe to be a very severe and elaborate case of cheating that took place on the just recently finished ICPC 2025 Online Winter Challenge powered by Huawei contest.
For context, the challenge is a 16 day contest with a large prize pool where contestants solve one optimization problem and aim for a score as high as possible. On the last day of the contest (precisely the last 6 hours), I was very surprised to find that multiple unrated accounts or accounts with minimal activity and background were able to unexpectedly replace the previous top scorers, earning them the places worthy of the first (8000 eur) or second (3000 eur) prize.
I was interested to learn who these brilliant competitors were since their profile gave me no information so I tried to google their usernames, mostly ending up with no results but one in particular led me to this very interesting blog on Codeforces about suspected cheaters on MaraTON Challenge 1 (also a contest with one optimization problem and a large prize pool) that took place about 1 year ago:
Before proceeding further, I would like you to first read the blog post I've linked. You may recognize one handle from the post if you participated in the Huawei contest. Namely, the 6th place in Huawei contest aliqi is mentioned as one of the suspected cheaters in the MaraTON contest. Interestingly they followed the same pattern in both contests, after sending a few weak solutions, they unexpectedly skyrocket to top scores, only this time as far as 6th place earning them first prize worth 8000 euros.
This doesn't prove anything but I've decided to dig deeper and noticed that two more accounts mentioned in the blog, onyeo and kvtan also participated in the Huawei challenge and placed in the top 50, both with the same pattern of "send a few weak solutions and then suddenly a brilliant one in the last hours of the contest".
Still this is not yet proof of anything, but the final twist came when I decided to read the comments of the MaraTON cheaters blog and one in particular caught my attention.
https://mirror.codeforces.com/blog/entry/138397#comment-1237360
The commenter, wltt, who fiercely defended the accused cheaters, also participated in Huawei and earned a top 50 finish with a very small amount of submissions. I decided to check if there is some publicly written code by each of these accounts as you cannot view the submissions on either MaraTON or Huawei and what I found amazed me.
I would like you to view these submissions by the following accounts:
These are all submissions during an active rated contest that these accounts took part in. Do you notice something? The template, coding style, indentation all appears to be EXACTLY the same. I have rarely (if ever) seen a person to decrement/increment a variable with a space between, like i ++ or i --, but ALL THREE of these accounts seem to do just that in each of their submissions. Along with the other extreme similarities in the code and the entire context involving these accounts I think I can without a doubt claim that accounts wltt aliqi kvtan are owned by the same person.
Another example of extreme similarities between the accounts are the only comments left by the accounts aliqi and kvtan on the Codeforces site.
aliqi https://mirror.codeforces.com/blog/entry/137533#comment-1239087
kvtan https://mirror.codeforces.com/blog/entry/137533#comment-1238978
Both seem to be extremely blatant AI written comments written one after another describing their approach to the MaraTON problem.
I think this case goes beyond usual cases of cheating as large amounts of prize money are in question. I expect something to be done about this as this is an insult to all legitimate contestants who spent hours and days on the contest only to have their spots taken in the last hours of the contest by this multi accounter.
Auto comment: topic has been updated by turneja (previous revision, new revision, compare).
This was just a single contest, and yet the cheaters we already know of (ranks 5, 6, 8, 37, 38) have pocketed over €20,000 in prize. That doesn’t even count the other unrated accounts that made only a few submissions (~20) and started submitting near the end — almost certainly cheaters as well. This is absolutely outrageous!
fatcat_me (rank 39) only made 6 submissions and used two different languages (C++ and Rust). How is this possible?
The question setter said that the data size was the same and there was no limit on the number of submissions. I submitted similar code many times in a row and tested the parameters. The account was blocked, so I had to create a new one and continue submitting. Because my account was blocked, I wasn't in the mood to continue. I just submitted the highest score I had achieved before. However, I think most of the previous participants should have tested the parameters and conducted offline scoring. The score difference was very small. Brother, are you feeling better now?
if your account really was blocked, what's your old handle? maybe one of the contest organizers or cf admins can give insight on why it was blocked.
"Have pocketed" isn't the right wording, it takes a while to release money so surely there's time to stop cheaters from receiving a single cent.