Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or filled with water. The vertices of the tree are numbered from 1 to n with the root at vertex 1. For each vertex, t…

Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or filled with water. The vertices of the tree are numbered from 1 to n with the root at vertex 1. For each vertex, t…

题目大概说给一棵树,进行以下3个操作:把某结点为根的子树中各个结点值设为1.把某结点以及其各个祖先值设为0.询问某结点的值. 对于第一个操作就是经典的DFS序+线段树了.而对于第二个操作,考虑再维护一个域表示各个结点为根的子树是否有进行第二个操作,如果有那么该结点应该就要是0:而在进行第一个操作前,看一下子树是否有进行第二个操作,如果有就整个标记成没有并把标记上传,让该结点的父亲结点标记成进行了第二个操作. #include<cstdio> #include<cstring> #i…

原题链接 题目大意 给定一棵根为1,初始时所有节点值为0的树,进行以下三个操作: 将以某点为根的子树节点值都变为1 将某个节点及其祖先的值都变为0 *询问某个节点的值 解题思路 这是一道裸的树链剖分题.下面详细地介绍一下树链剖分. 树链剖分预备知识: 线段树.DFS序 树链剖分想法|起源 首先,如果一棵树退化成一条链,那么它会有非常好的性质.我们可以用线段树等数据结构来维护相关操作,使得效率更高.那么我们考虑一般的树,它是否能被分成一些链,使它们也能更高效地进行某些操作? 算法流程 以下以点带权…

题意简述 维护一棵树,支持以下操作: 0 v:将以v为跟的子树赋值为1 1 v:将v到根节点的路径赋值为0 2 v:询问v的值 题解思路 树剖+珂朵莉树 代码 #include <set> #include <cstdio> #define IT std::set<Node>::iterator const int N=500005; int n,q,u,v,opt,x,cnt; int h[N],to[N<<1],nxt[N<<1]; int…

Water Tree CodeForces 343D 树链剖分+线段树 题意 给定一棵n个n-1条边的树,起初所有节点权值为0. 然后m个操作, 1 x:把x为根的子树的点的权值修改为1: 2 x:把x结点到根路径上的点修改为0: 3 x:查询结点x的值. 解题思路 这个因为是在树上进行的操作,所以首先需要把树进行一些转化,比如使用dfs序列转变成一维的,这样方便使用线段树或则树状数组来进行操作.但是因为这里的操作2需要把x节点和它的父节点赋值为0,所以需要树链剖分来进行处理. 关于树链剖分的讲…

D. Water Tree   Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or filled with water. The vertices of the tree are numbered from 1 to n with the root at vertex 1. Fo…

D. Water Tree Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/343/problem/D Description Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or…

Water Tree 给出一棵树,有三种操作: 1 x:把以x为子树的节点全部置为1 2 x:把x以及他的所有祖先全部置为0 3 x:询问节点x的值 分析: 昨晚看完题,马上想到直接树链剖分,在记录时间戳时需要记录一下出去时的时间戳,然后就是很裸很裸的树链剖分了. 稳稳的黄名节奏,因为一点私事所以没做导致延迟了 (ps:后来想了一下,不用树链剖分直接dfs序维护也行...) #include <set> #include <map> #include <list> #i…

D. Water Tree time limit per test 4 seconds memory limit per test 256 megabytes input standard input output standard output Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either…