cip999's blog

By cip999, history, 5 months ago, In English

Hello Codeforces!

Thanks for taking part in the SWERC 2021-2022 mirror. We hope you enjoyed thinking about the problems.

The contest was intended for a wide range of participants. As such, there were "very easy" to "easy" problems (A, M, H) as well as extremely challenging ones (B and J, neither of which appeared in the official contest, together with C). Some problems demanded the knowledge of specific techniques, algorithms or data structures (e.g. E, G, K, J), while others were purely based on insight and deduction (B, D, N).

But without further ado, let's present the editorial!


Solutions



Solution of Problem A

Statement by dario2994, preparation by dario2994


Solution of Problem B

Statement by Giove, preparation by Giove


Solution of Problem C

Statement by gangsterveggies, preparation by gangsterveggies


Solution of Problem D

Statement by tap_tapii, preparation by tap_tapii


Solution of Problem E

Statement by Petr, preparation by Petr


Solution of Problem F

Statement by Simon, preparation by majk


Solution of Problem G

Statement by cescmentation_folch, preparation by cescmentation_folch


Solution of Problem H

Statement by majk, preparation by majk


Solution of Problem I

Statement by tap_tapii, preparation by gangsterveggies


Solution of Problem J

Statement by Simon, preparation by Simon


Solution of Problem K

Statement by gog.gerard, preparation by gog.gerard


Solution of Problem L

Statement by gog.gerard, preparation by gog.gerard


Solution of Problem M

Statement by cip999, preparation by cip999


Solution of Problem N

Statement by cip999, preparation by Delfad0r


Solution of Problem O

Statement by Simon, preparation by Simon

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By cip999, 14 months ago, In English

We hope you liked the problems! Before we go ahead with the editorial, let us make some general comments about this round.

Problems A, B, C, D, E, F are "div 2" problems, while problems G, H, I are meant to be solved by Grandmasters. Overall, our goal was to provide a problemset that could be enjoyable for a wide range of participants and such that the winner could solve all the problems.

There were three big "jumps" in the difficlty gaps between consecutive problems. Problems A and B are meant to be easy, many contestants have the skills and the techniques to attack them (and, maybe, to solve them). Problems C, D, E, F are gradually harder but the difficulty gap between C and F is not as large as usual (and this is reflected in the score distribution). The same holds for problem G, H, I; the difficulty gap between G and I is relatively small (but there is a big score difference because coding I is much harder). Sadly, we discovered 14 minutes into the round that problem I has already appeared in a contest (most likely also in Polish contest, if you know it please tell us in the comments). See also this comment.


Pre-contest predictions


Detailed overview on the problemset and a bit of behind-the-scenes


Which author did what?


Some thoughts from cip999


Hints and solutions


A


B


C


D


E


F


G


H


I

If you find any typo, feel free to tell us with a comment. Moreover, if you want to share your opinion on the problemset, we are eager to read it.

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