Abandoned country 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5723 Description An abandoned country has n(n≤100000) villages which are numbered from 1 to n. Since abandoned for a long time, the roads need to be re-built. There are m(m≤1000000) ro…

Abandoned country Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 4477    Accepted Submission(s): 1124 Problem Description An abandoned country has n(n≤100000) villages which are numbered from 1…

Abandoned country Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 3006    Accepted Submission(s): 346 Problem Description An abandoned country has n(n≤100000) villages which are numbered from 1…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5723 题意:求最小生成树,并且求这棵最小生成树上所有边走过次数的期望. 走过次数的期望=Σ边被走过次数*边权/(n*(n-1)/2) 求边被走过的次数,相当于关心这个边的两侧分别有多少点,走的次数就是两边的点数的乘积这个很好理解.可以从边的一侧开始dfs,找到这个边的一侧点数x,由于最小生成树是联通的,那么边的另一侧点数一定是n-x.所以这条边的贡献是(n-x)*x*w. #include <bit…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5723 n个村庄m条双向路,从中要选一些路重建使得村庄直接或间接相连且花费最少,这个问题就是很明显的求最小生成树,由于边权各不相同,所以最小生成树唯一. 然后,在这个最小生成树的基础上,求各个路径的最小期望和(推导出 期望 = 所有村庄中任意两个村庄距离之和 / 村庄对数). 最小生成树很好求(边权从小到大,并查集一下就好了). 然后求以上基础村庄中任意两个村庄距离之和,只要求每条边乘上每条边出现的次…

#include<bits/stdc++.h> using namespace std; struct node{ int u, v, w, nex; bool gone; node(){} node(int a,int b,int c){ u = a;v = b;w = c;gone = false; } bool operator <(const node&a)const{ return w < a.w; } }; ; ; node Gra[maxE]; int dp[…

任意门:http://acm.hdu.edu.cn/showproblem.php?pid=5723 Abandoned country Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 7573    Accepted Submission(s): 1850 Problem Description An abandoned country…

http://acm.hdu.edu.cn/showproblem.php?pid=5723 Abandoned country Problem Description   An abandoned country has n(n≤100000) villages which are numbered from 1 to n. Since abandoned for a long time, the roads need to be re-built. There are m(m≤1000000…

Abandoned country Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1756    Accepted Submission(s): 475 Problem Description An abandoned country has n(n≤100000) villages which are numbered from 1…

题目链接:hdu 5723 Abandoned country 题目大意:N个点,M条边:先构成一棵最小生成树,然后这个最小生成树上求任意两点之间的路径长度和,并求期望 /************************************************************** Problem:hdu 5723 User: youmi Language: C++ Result: Accepted Time:2932MS Memory:22396K solution:首先注意到任…