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…

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…

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.…

[链接] 我是链接,点我呀:) [题意] 在这里输入题意 [题解] 从根节点开始. 显然它是什么颜色.就要改成对应的颜色.(如果上面已经有某个点传了值就不用改 然后往下传值. [代码] #include <bits/stdc++.h> using namespace std; const int N = 1e4; int n,c[N+10],ans; vector <int> g[N+10]; void dfs(int x,int C){ int flag = C; if (C!=…

A. Visiting a Friend time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Pig is visiting a friend. Pig's house is located at point 0, and his friend's house is located at point m on an axis. Pi…

// 从大作业和实验报告中爬出来水一发 // 补题...还是得排在写完实验报告之后... A. Visiting a Friend 题意 给定若干段行车区间,问能否从起点到终点 思路 扫描一遍,维护最远的终点 Code #include <bits/stdc++.h> using namespace std; typedef long long LL; int x[110], y[110]; int main() { int n, m; scanf("%d%d", &…

Visiting a Friend Solution Coloring a Tree 自顶向下 Solution Hashing Trees 连续2层节点数都超过1时能异构 Solution GCD of Polynomials 斐波那契数列为什么那么重要,所有关于数学的书几乎都会提到? - 王希的回答 - 知乎 https://www.zhihu.com/question/28062458/answer/39763094 Solution Bipartite Segments Weightin…

C. Coloring Trees time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder and Chris the Baboon has arrived at Udayland! They walked in the park where ntrees grow. They decided to be n…

之前两次遇到过函数的思想的题,所以这次很敏感就看出来了.可以参考之前的题: https://www.cnblogs.com/hua-dong/p/9291507.html Christmas is coming! Eddy has received a Christmas tree as gift. Not surprisingly, the tree consists of N vertices and N-1 edges and magically remains connected. Cu…

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 given colors…