分治.选最左上的点分给根.剩下的极角排序后递归 C. Paint Tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a tree with n vertexes and n points on a plane, no three points lie on one straight line…

E - Paint Tree You are given a tree with n vertexes and n points on a plane, no three points lie on one straight line. Your task is to paint the given tree on a plane, using the given points as vertexes. That is, you should correspond each vertex of…

C. Paint Tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a tree with n vertexes and n points on a plane, no three points lie on one straight line. Your task is to paint…

题目链接 Paint Tree 给你一棵n个点的树和n个直角坐标系上的点,现在要把树上的n个点映射到直角坐标系的n个点中,要求是除了在顶点处不能有线段的相交. 我们先选一个在直角坐标系中的最左下角的点,把根结点放到这个点中,然后对剩下的点进行极角排序,按逆时顺序一个个塞进来,类似地递归处理. 这样就满足了题意. #include <bits/stdc++.h> using namespace std; #define rep(i, a, b) for (int i(a); i <= (b…

题目链接:Codeforces 461B Appleman and Tree 题目大意:一棵树,以0节点为根节点,给定每一个节点的父亲节点,以及每一个点的颜色(0表示白色,1表示黑色),切断这棵树的k条边,使得树变成k+1个联通分量.保证每一个联通分量有且仅有1个黑色节点.问有多少种切割方法. 解题思路:树形dp,dp[i][0]和dp[i][1]分别表示子树一下的切割方法中,i节点所在联通块不存在黑节点和已经存在一个黑节点的方案数. #include <cstdio> #include &l…

Codeforces 1129 E.Legendary Tree 解题思路: 这题好厉害,我来复读一下官方题解,顺便补充几句. 首先,可以通过询问 \(n-1​\) 次 \((S=\{1\},T=\{2\dots n\},i),i\in[2,n]​\) ,来得到以 \(1​\) 为根树的所有节点的子树大小. 然后考虑从子树大小最小的节点开始,为每一个节点找它们的儿子,由于每个节点儿子的子树大小,一定小于这个节点的子树大小,所以可以按照子树大小从小到大排序,每个节点的儿子就一定在其前面. 假设已经…

Codeforces 280C Game on tree LINK 题目大意:给你一棵树,1号节点是根,每次等概率选择没有被染黑的一个节点染黑其所有子树中的节点,问染黑所有节点的期望次数 #include<bits/stdc++.h> using namespace std; #define N 100010 int n,tot=0,head[N]={0}; struct Edge{int v,nxt;}E[N<<1]; void add(int u,int v){ E[++tot…

Link: Codeforces #196 传送门 A: 枚举 #include <bits/stdc++.h> using namespace std; #define X first #define Y second typedef long long ll; typedef pair<int,int> P; ; <<; int main() { scanf("%d%d",&n,&m); ;i<=m;i++) scanf(&…

题目描述: Game on Tree time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Momiji has got a rooted tree, consisting of n nodes. The tree nodes are numbered by integers from 1 to n. The root has num…

Codeforces Round #781 C. Tree Infection time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output A tree is a connected graph without cycles. A rooted tree has a special vertex called the root. The p…