Codeforces Round #528 (Div. 2) - D. Minimum Diameter Tree

AC

在树的边缘上分配权值，使得树上最大路径权值和最小。
因为是在树的边缘上分配权值，所有所有的中间节点（非叶子节点）的权值为0，这样树上任意两点的距离最大就是一条包含两个边缘节点的路径。
统计所有边缘节点（叶子节点）的数目，计算每个节点的权值，然后两个权值和就是答案。

#include <bits/stdc++.h>
#define P pair<int, int>
#define lowbit(x) (x & -x)
#define mem(a, b) memset(a, b, sizeof(a))
#define REP(i, n) for (int i = 1; i <= (n); ++i)
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define N 200006
#define LL  long long
using namespace std;int sum[N];
int main() {#ifndef ONLINE_JUDGEfreopen("in.txt", "r", stdin);
#endifint n, s;while (scanf("%d %d", &n, &s) != EOF) {mem(sum, 0);int u, v;rep (i, n-1){scanf("%d %d", &u, &v);sum[u]++;sum[v]++;}int tot = 0;REP (i, n) {if (sum[i] == 1)    tot++;}printf("%.6lf\n", s * 1.0 / tot * 2);}return 0;
}

Codeforces Round #528 (Div. 2) - D. Minimum Diameter Tree相关推荐

Codeforces Round #453 (Div. 1) D. Weighting a Tree 构造 + dfs树
传送门文章目录题意: 思路: 题意: 给你一颗nnn个点的图,每个点都有一个点权cic_ici,要求你给每个边赋一个权值kik_iki,要求对于每个点与他相连的边的权值之和等于这个点的点权ci ...
Codeforces Round #319 (Div. 1) B. Invariance of Tree 构造
B. Invariance of Tree Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/576/ ...
Codeforces Round #528 (Div. 2, based on Technocup 2019 Elimination Round 4) C. Connect Three 【模拟】...
传送门:http://codeforces.com/contest/1087/problem/C C. Connect Three time limit per test 1 second memor ...
[CF]Codeforces Round #528 Div.2
Div.2还是稳定四题啊,E题还是没得办法,就争取四题再快点吧. A(签到) 题意:写下s的第一个字符,在最右边写下s的第二个字符,在最左边写下s的第三个字符,以此类推生成字符串t,给出t,求s 找规 ...
Codeforces Round #753 (Div. 3) C. Minimum Extraction（最小抽离）
题目翻译: Yelisey has an array a of n integers. 数组a中有n个整数 If a has length strictly greater than 1, then ...
Codeforces Round #379 (Div. 2) E. Anton and Tree —— 缩点 + 树上最长路
题目链接:http://codeforces.com/contest/734/problem/E E. Anton and Tree time limit per test 3 seconds mem ...
Codeforces Round #263 (Div. 2) D. Appleman and Tree 树形dp
链接: http://codeforces.com/contest/462/problem/D 题意: 给定n个点的树, 0为根,下面n-1行表示每个点的父节点最后一行n个数表示每个点的颜色,0为 ...
Codeforces Round #263 (Div.1) B. Appleman and Tree
题目地址:http://codeforces.com/contest/461/problem/B 题目大意:给一棵树.每一个点为白色或黑色.切断一些边,使得每一个连通块有且仅有一个黑点,问划分方案数. ...
Codeforces Round #530 (Div. 1) C. Construct a tree 想法
题目链接:http://codeforces.com/contest/1098/problem/C 题意: 给你n个点要你组成一棵以结点1为根的树,使得所有结点的子树的大小和为s,且在这种情况下使得分 ...

Codeforces Round #528 (Div. 2) - D. Minimum Diameter Tree

AC

Codeforces Round #528 (Div. 2) - D. Minimum Diameter Tree相关推荐

最新文章

热门文章