Several months passed before there was enough free time to create this blog post, but approximately 300 cheaters were identified in this round, and they still remain unbanned.

What happened? Some deliberately misleading solutions were leaked for problems D and F on Telegram, complete with a nonsensical “antihack.” It would seem unlikely that anyone would be fooled, yet they were. A few participants even went so far as to modify their “antihack” in an effort to avoid being caught (279632291 279636420 279589162, among others). All of these attempts were ultimately hacked.

In fact, anyone who was hacked on these problems can be considered a cheat. The same applies to most people who received WA10 on D (there were a few exceptions) and pretty much everyone who got WA7 (and beyond) on F.

Also, special mention to these obvious cheats who changed their antihack such that it became unhackable. 279564544 279576359 279596731 279583754 279616385 279631335 and I'm sure there are others.

MikeMirzayanov Please ban everyone here: hacked on problem D and here: hacked on problem F

It was way too much fun trying to generate all these hack cases for the different people who tried to be clever and change the antihack logic, but I'm very sad to see that no-one has been banned based on this.