Hi Codeforces!

When I was browsing around, I noticed this weird occurrence in contest.

Furthermore, his solutions look correct, so it wasn't some WA not showing up.

So, 2018030402055, have you received any updates? MikeMirzayanov, can you correct this?

This user shouldn't lose rating when they got AC on these problems.

Hi Codeforces,

As I've begun to compete more frequently, I've noticed that quite a few recent contests have ended in a large number of solutions being hacked, leading me to frequently jump hundreds of places.

Some examples: https://mirror.codeforces.com/contest/1182 (B), https://mirror.codeforces.com/contest/1187 (D). (I am not hating on these contests at all, just using them as examples. In fact, I very much enjoyed the problems in both contests.)

I've also heard of a lot of hacks in other contests that occur, such as CodeCraft, where people fail multiple problems from hacks.

So I'm wondering:

1.) Has anyone noticed a similar trend? Is it getting worse?

2.) Is there something that problem setters/testers can do to stop this, or at least minimize its occurrence?

3.) Also, what makes some contests virtually hack-free, while others have so many?

If anyone has any insight, please share it below.