Hello Codeforces.

I am writing this post to apologize for some issues with round 659. Among them:

• Problem D2B was definitely too hard for its position, as indicated by number of solves. Also, its statement was lengthy and it seems that many participants had troubles understanding it. Although I still like this problem a lot, we just should have used another problem
• The gap between Div1AB and Div1CDEF in Div1 round was enormous, and we couldn't predict the order of problems well.
• The constraints of the problem D1F were too tight, even more, at the moment we don't have a solution which would pass all hacks from Japan Mafia. This is completely my fault, I should have forced smaller constraints, especially after Um_nik told me about this.

Of course, I feel very disappointed about this situation. I will try to improve in difficulty estimation, but with this kind of problems even with a lot of testers it's hard to determine the best order. I will try to improve testing, to analyze its results with more attention. I believe that future rounds will be great and very balanced as well. And I will definitely pay much more attention to the choice of constraints in upcoming rounds.

Q: Is round rated?

A: Yes!

While issues with balance are unfortunate, they can't contribute to whether round is rated. The last issue is more complicated. However, after discussion with MikeMirzayanov, we agreed that the round remains rated. The problem played its role in the round, and during the round, I think, very small number of people who came up with intended sol didn't implement it because of thinking that it would be too slow.

I also don't really see how whether we succeed in optimizing our sol to make it pass all the hacks may relate to the results of the round, to be honest (current sol works in 6.4 sec on the hacks).

Again, I am really really sorry for all the issues :(. This is my fault. I will do my best for this to not repeat. I really hope you at least enjoyed the problems.

For the upsolving, though, we are thinking on decreasing the constraints to something adequate, or on increasing TL to something inadequate. If you have another ideas, feel free to share in comments.

Anton

P.S.

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