http://codeforces.com/problemset/problem/570/D Tree Requests time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a lowercase…

链接 题解链接:点击打开链接 题意: 给定n个点的树.m个询问 以下n-1个数给出每一个点的父节点,1是root 每一个点有一个字母 以下n个小写字母给出每一个点的字母. 以下m行给出询问: 询问形如 (u, deep) 问u点的子树中,距离根的深度为deep的全部点的字母是否能在随意排列后组成回文串,能输出Yes. 思路:dfs序,给点又一次标号,dfs进入u点的时间戳记为l[u], 离开的时间戳记为r[u], 这样对于某个点u,他的子树节点相应区间都在区间 [l[u], r[u]]内. 把距…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 36442   Accepted: 10894 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has bee…

Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been carefully nurturing the big apple tree. The tree has N forks which are connected by branches.…

http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=10486 题意:一颗有n个分支的苹果树,根为1,每个分支只有一个苹果,给出n-1个分支的关系和给出m个操作,Q x表示询问x的子树(包括x)苹果的数量,C x表示若分支x上有苹果,则摘下来,若没有则会生出一个,输出每个询问的值. DFS序 每个子树对应的孩子节点包括根用dfs序存在连续区间中,用树状数组维护区间 //#pragma comment(linker, "/STAC…

题目大意:对树进行m次操作,有两类操作,一种是改变一个点的权值(将0变为1,1变为0),另一种为查询以x为根节点的子树点权值之和,开始时所有点权值为1. 分析: 对树进行dfs,将树变为序列,记录每个点进栈出栈的时间戳作为其对应区间的左右端点,那么其子节点对应区间必在该区间内,对这段区间求和即可,用树状数组进行修改与求和. 代码: program apple; type point=^node; node=record x:longint; next:point; end; var a:..]o…

题目链接:https://codeforces.com/problemset/problem/570/D 题解: 这种题,基本上容易想到DFS序. 然后,我们如果再把所有节点分层存下来,那么显然可以根据 $in[v],out[v]$ 在层内二分出一段属于 $v$ 的子树的节点. 那么我们进一步考虑,如果把一层的节点,按 $a \sim z$ 再分开来,用一个 $S[c][d]$ 数组来存所有字母为 $c$,深度为 $d$ 的节点的 $in[]$ 值. 这样一来,对于一个询问 $v,h$,就在 $…

C. Propagating tree Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/383/problem/C Description Iahub likes trees very much. Recently he discovered an interesting tree named propagating tree. The tree consists of n nodes numb…

C. Propagating tree Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/383/problem/C Description Iahub likes trees very much. Recently he discovered an interesting tree named propagating tree. The tree consists of n nodes numb…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5293 题意: 给你一些链,每条链都有自己的价值,求不相交不重合的链能够组成的最大价值. 题解: 树形dp, 对于每条链u,v,w,我们只在lca(u,v)的顶点上处理它 让dp[i]表示以i为根的指数的最大值,sum[i]表示dp[vi]的和(vi为i的儿子们) 则i点有两种决策,一种是不选以i为lca的链,则dp[i]=sum[i]. 另一种是选一条以i为lca的链,那么有转移方程:dp[i]=…