Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n its vertices, so that the i-th vertex gets color ci. Now it's time for Timofey birthday, and his mother asked him to remove the tre…

A. Timofey and a tree 题意:给一棵树,要求判断是否存在一个点,删除这个点后,所有连通块内颜色一样.$N,C \le 10^5$ 想法:这个叫换根吧.先求出一个点合法即其儿子的子树内颜色一样,非该点子树的点颜色都一样.可以用DFS序解决. #include< cstdio > typedef long long ll; template inline void read(T&x) { x=0;bool f=0;char c=getchar(); while((c&l…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n its vertices, so that the…

地址:http://codeforces.com/contest/764/problem/C 题目: C. Timofey and a tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Each New Year Timofey and his friends cut down a tree of n vertices…

A. Timofey and a tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n…

codeforces 741D Arpa's letter-marked tree and Mehrdad's Dokhtar-kosh paths 题意 给出一棵树,每条边上有一个字符,字符集大小只有22. 对于每一个子树,询问其中最长的,满足:路径上的字符集可以重组成字符串的路径的长度. 题解 明显是用mask维护信息,然后启发式合并一下. 一般启发式合并需要用map维护信息,这样的复杂度是log^2的.如果保留每个点重儿子的信息,就可以用全局变量维护,全局变量的大小就可以开很大,可以做到l…

codeforces 812E Sagheer and Apple Tree 题意 一棵带点权有根树,保证所有叶子节点到根的距离同奇偶. 每次可以选择一个点,把它的点权删除x,它的某个儿子的点权增加x.点权中途中不能为负.如果选中的是叶子节点,则只删除它的点权. 两个人玩博弈,后手可以先交换两个点点权,问有多少种方法使得他必胜? 题解 观察一下可以发现,把和叶节点同奇偶的那些点拉出来,相比nim博弈多了一种操作:增加一些石子在某堆.不过本质不会有什么变化,因为如果A选择增加,B可以选择减少相同的…

题目链接 codeforces 220 C. Game on Tree 题解 对于 1节点一定要选的 发现对于每个节点,被覆盖切选中其节点的概率为祖先个数分之一,也就是深度分之一 代码 #include<cstdio> #include<algorithm> const int maxn = 1000007; struct node { int u,v,next; } edge[maxn << 1] ; int head[maxn],num = 0; inline vo…

题目描述: Alyona and a tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Alyona has a tree with n vertices. The root of the tree is the vertex 1. In each vertex Alyona wrote an positive int…

package codeforces; import java.util.*; public class CodeForces_764C_Timofey_and_a_tree { static final int N=(int) (2e5+10); @SuppressWarnings("unchecked") static ArrayList<Integer> a[]=new ArrayList[N]; static int book[]=new int[N]; stati…