Hello,
Our training contest in Xidian University, named 2020-2021 “Orz Panda” Cup Programming Contest will start on Nov. 22, 2020.
The problems are prepared by Xi Ruoyao (me, loujunjie) and Wang Xiaoqing (qkoqhh). Thanks Huang Haitong (fffasttime) for testing the problems. And thanks MikeMirzayanov for Polygon and Codeforces.
The online mirror will start at 22.11.2020 09:00 (Московское время), one hour after the onsite training contest starts. Unfortunately I can't make the mirror public now, because some participant of the onsite round has Codeforces coach rights (for example flukehn). I will make it public after the onsite round starts.
We will select ICPC regional teams from the candidates in Xidian University, by the ranking of this training contest. The problems are easier than ICPC regionals though we tried to make them regional-like.
The training round is for teams, but both teams and individuals can take part in the online mirror.
The “Orz Panda” is a lovely figure we often use to show respect to others.
If you decide to take part in, thanks for support. If not, thanks for reading my bad English.
UPD1: Congratulations to team Symplectic Geometric Rhythm (flukehn, bzy, and danihao123), who won the contest with 7 problems solved! The ghosts and tutorial will be uploaded soon.
UPD2: The ghosts and tutorial have been uploaded.
Auto comment: topic has been updated by loujunjie (previous revision, new revision, compare).
Auto comment: topic has been updated by loujunjie (previous revision, new revision, compare).
The sponsor Xi Ruoyao said "He and qkoqhh have exhausted all their lives' learning to prepare tomorrow's problems for us" yesterday. So I will thank god if I am able to solve one problem.
Then your team solved 7 problems :).
Waiting for tutorial qwq
Is there some typo in solution D? I think the last line should be
Or I misunderstand the formula...
Yes. I've updated the tutorial. Sorry for the stupid mistake :(.
What is apiadu's sieve? Seems to be a well-known algorithm in China, but I couldn't find it in English.
I believe it is the same as what is described in this blog. This comment also gives a way to find the prefix sum of the totient function.