Difference between revisions of "Training 1: (Persistent) Segment Tree"
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== Problem K == | == Problem K == | ||
− | + | Solved by Xiejiadong. | |
+ | |||
+ | 主席树。 | ||
+ | |||
+ | 求区间第$k$小数,权值线段树,差分维护。 | ||
+ | |||
+ | 在线段树上二分即可。 |
Revision as of 03:21, 22 April 2019
Problem A
Solved by Weaver_zhu.
Problem from HDU4578.
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
Solved by Xiejiadong.
Problem from BZOJ3551.
主席树。
BZOJ3545和BZOJ3551题目一样,只不过3551要求强制在线。
因为我的做法BZOJ3545也是支持在线的,所以就无所谓了。
[题解]
Problem I
Solved by Xiejiadong.
Problem from Codeforces242E.
看到异或,考虑拆位。
维护 $20$ 棵线段树,对于每一位需要维护一个 tag 表示当前有没有置反,维护区间和即可。
Problem J
Unsolved.
Problem K
Solved by Xiejiadong.
主席树。
求区间第$k$小数,权值线段树,差分维护。
在线段树上二分即可。