Can anyone give me some tips about solving constructives quickly on codeforces pls? Now what I'm doing is smth like random guessing (I cannot find the right method quick often), and if I failed, I get stuck on that problem for a long time!

Example: In Codeforces Round 953 (Div. 2) I get stuck on C (constructive) for about 40min and therefore get a low ranking(although I solved D and E fast). This kind of things often happens on me and that's kinda annoying.

Sorry for poor English. Any help will be appreciated.

Is this rating graph normal? Nearly reached master and then falling back to expert in 5 rounds?

Thanks to Farmer John for his great contribution. He killed me three times this year(two of them were usaco).So sad:(

Anyway this is skill issue.Hope to get better next time.

Link:https://codeforces.me/gym/104686/problem/F

Actually I have trouble reading the editorial(it's too brief for me to understand),so now I'm here trying to get a more detailed editorial of this problem.If anyone knows the solution,help me pls.