Description You are given a rooted tree with n vertices. The vertices are numbered from 1 to n, the root is the vertex number 1. Each vertex has a color, let's denote the color of vertex v by cv. Initially cv = 0. You have to color the tree into the…

B. Coloring a Tree 题目链接: https://codeforces.com/contest/902/problem/B 题意:给你一颗树,原先是没有颜色的,需要你给树填色成指定的样子,每次填色的话,子树会和根节点变成同一种颜色,问需要多少次填色 题解:前向星建树,从每个父节点便利,如果父节点的颜色和子节点不一样就ans++吗,最后记得把第一次操作(根节点涂色的次数 给记上 代码如下: #include <map> #include <set> #include…

思维 这道题应该算是一道思维题吧. 首先你要想到,既然这是一棵无根树,就要明智地选择根--以第一个黑点为根(不要像我一样习惯性以\(1\)号点为根,结果直到心态爆炸都没做出来). 想到这一点,这题就很简单了. 具体 设\(p_i\)为从\(i\)到根路径上的最小值,考虑一个黑点\(y\)对于\(x\)号点的贡献. 显然这一贡献就是将\(x\)的答案向\(y\)到\(LCA(x,y)\)路径上的最小值取\(min\). 而由于\(LCA(x,y)\)到根路径上的最小值也是\(x\)到根路径上的最小…

Binary Tree Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 138    Accepted Submission(s): 73 Special Judge Problem Description The Old Frog King lives on the root of an infinite tree. Accordin…

题目链接 Problem Description HazelFan wants to build a rooted tree. The tree has n nodes labeled 0 to n−1, and the father of the node labeled i is the node labeled ⌊i−1k⌋. HazelFan wonders the size of every subtree, and you just need to tell him the XOR…

B. Destruction of a Tree time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given a tree (a graph with n vertices and n - 1 edges in which it's possible to reach any vertex from any ot…

Problem Description Coach Pang is interested in Fibonacci numbers while Uncle Yang wants him to do some research on Spanning Tree. So Coach Pang decides to solve the following problem:Consider a bidirectional graph G with N vertices and M edges. All…

Description A family consisting of father bear, mother bear and son bear owns three cars. Father bear can climb into the largest car and he likes it. Also, mother bear can climb into the middle car and she likes it. Moreover, son bear can climb into…

Code: #include<bits/stdc++.h> #define ull unsigned long long #define MOD 1000000007 #define ll long long #define maxn 120000 using namespace std; void setIO(string s) { string in=s+".in"; string out=s+".out"; freopen(in.c_str(),&…

传送门:http://codeforces.com/contest/902/problem/B 本题是一个关于“树”的问题. 有一棵n个结点的有根树,结点按照1~n编号,根结点为1.cv为结点v的色号,初始化为0.每一步选定一个结点v和一个色号x,于是v和v的所有后代结点均被染色,色号为x. 给定一个色号表{cv|v=1,2,...,n},满足1≤cv≤n,其中cv是结点v应该被染成的色号.求完成染色的最小操作步数. 注意到,若对结点v染色,色号为x,则v和v的所有后代结点均被染色,色号也为x.…