2019牛客暑期多校训练营第 9 场

rank solved A B C D E F G H I J
37 6 . O O O O . . Ø . O

B

Solved by Forsaken.

二次剩余。

C

Solved by Henry.

D

Solved by XLor.

折半搜索。

E

Solved by Forsaken.

并查集。

H

UpSolved by XLor.

主席树。(不知道为啥赛中一直过不了)

J

Solved by XLor.

对称轴一定在某个端点或中点。

关键点抠出来扫描线即可。