Training 1: (Persistent) Segment Tree

Problem A

Solved by Weaver_zhu.

Problem B

Solved by Xiejiadong.

Problem form BZOJ1818.

题意：如果一个点位于四个黑点之间，那么他可以变成白点，求最后有多少个白点。

题解：对于行和列分别求出 max 和 min ，就可以得到行和列的作用域。

于是就是求行和列两两之间的交点个数。

我们用线段树维护列，用扫描线扫描行，遇到左端点的时候对那一列 +1 ，遇到右端点的时候，对那一列 -1 。每次询问一个区间和就行了。

Problem C

Unsolved.

Problem D

Solved by Xiejiadong.

Problem from BZOJ3261.

可持久化字典树。

[题解]

Problem E

Unsolved.

Problem F

Solved by Xiejiadong.

Problem from Codeforces1080F.

主席树。

[题解]

Problem G

Unsolved.

Problem H

Unsolved.

Problem I

Unsolved.

Problem J

Unsolved.

Problem K

Unsolved.