poj 1258 Agri-Net(最小生成树果题)

题目链接:http://poj.org/problem?id=1258

Description

Farmer John has been elected mayor of his town! One of his campaign promises was to bring internet connectivity to all farms in the area. He needs your help, of course.

Farmer John ordered a high speed connection for his farm and is going to share his connectivity with the other farmers. To minimize cost, he wants to lay the minimum amount of optical fiber to connect his farm to all the other farms.

Given a list of how much fiber it takes to connect each pair of farms, you must find the minimum amount of fiber needed to connect them all together. Each farm must connect to some other farm such that a packet can flow from any one farm to any other farm.

The distance between any two farms will not exceed 100,000.

Input

The input includes several cases. For each case, the first line contains the number of farms, N (3 <= N <= 100). The following lines contain the N x N conectivity matrix, where each element shows the distance from on farm to another. Logically, they are N lines
of N space-separated integers. Physically, they are limited in length to 80 characters, so some lines continue onto others. Of course, the diagonal will be 0, since the distance from farm i to itself is not interesting for this problem.

Output

For each case, output a single integer length that is the sum of the minimum length of fiber required to connect the entire set of farms.

Sample Input

4
0 4 9 21
4 0 8 17
9 8 0 16
21 17 16 0

Sample Output

28

Source

USACO 102

代码如下:

#include <stdio.h>
#include <string.h>
#define INF 0x3f3f3f3f
#define MAXN 517
//创建m二维数组储存图表,low数组记录每2个点间最小权值,visited数组标记某点是否已访问
int m[MAXN][MAXN], low[MAXN], visited[MAXN];
int n;
int prim( )
{
    int i, j;
    int pos, minn, result=0;
    memset(visited,0,sizeof(visited));
    visited[1] = 1;
    pos = 1;          //从某点开始,分别标记和记录该点
    for(i = 1; i <= n; i++)     //第一次给low数组赋值
        if(i != pos)
            low[i] = m[pos][i];
        else
            low[i] = 0;
    for(i = 1; i < n; i++) //再运行n-1次
    {
        minn = INF;   //找出最小权值并记录位置
        for(j=1; j<=n; j++)
        {
            if(visited[j]==0 && minn>low[j])
            {
                minn = low[j];
                pos = j;
            }
        }
        result += minn;   //最小权值累加
        visited[pos] = 1;   //标记该点
        for(j = 1; j <= n; j++)   //更新权值
            if(visited[j]==0 && low[j]>m[pos][j])
                low[j] = m[pos][j];
    }
    return result;
}
int main()
{
    int i,j,ans;
    while(scanf("%d",&n)!=EOF)
    {
        memset(m,INF,sizeof(m));   //所有权值初始化为最大
        for(i = 1; i <= n; i++)
            for(j = 1; j <= n; j++)
            {
                scanf("%d",&m[i][j]);
            }
        ans=prim( );
        printf("%d\n",ans);
    }
    return 0;
}

poj 1258 Agri-Net(最小生成树果题)

时间: 08-18

poj 1258 Agri-Net(最小生成树果题)的相关文章

poj 1258 Agri-Net (最小生成树 prim)

Agri-Net Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 39499   Accepted: 16017 Description Farmer John has been elected mayor of his town! One of his campaign promises was to bring internet connectivity to all farms in the area. He nee

POJ 1258 Agri-Net (prim最小生成树)

最小生成树模板题 #include<bits/stdc++.h> using namespace std; int n,a; int dist[120],m[120][120]; void prim() {     bool p[1020];     for(int i=2;i<=n;i++)     {         p[i]=false;         dist[i]=m[1][i];     }     dist[1]=0,p[1]=true;     for(int i=1;

POJ 1258 Agri-Net(最小生成树 Kruskal)

题意  给你农场的邻接矩阵  求连通所有农场的最小消耗 和上一题一样裸的最小生成树 #include<cstdio> #include<cstring> #include<algorithm> using namespace std; const int N = 105, M = 10050; int par[N], ans, n, m, t; struct edge { int u, v, w;} e[M]; bool cmp(edge a, edge b){ ret

poj 1258 Agri-Net【最小生成树(prime算法)】

Agri-Net Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 44827   Accepted: 18351 Description Farmer John has been elected mayor of his town! One of his campaign promises was to bring internet connectivity to all farms in the area. He nee

POJ 1258 Agri-Net(最小生成树)

Description Farmer John has been elected mayor of his town! One of his campaign promises was to bring internet connectivity to all farms in the area. He needs your help, of course. Farmer John ordered a high speed connection for his farm and is going

POJ - 1258 Agri-Net (最小生成树)

https://vjudge.net/problem/POJ-1258 模板题,没啥好说的. #include<iostream> #include<cmath> #include<cstring> #include<queue> #include<vector> #include<cstdio> #include<algorithm> #include<map> #include<set> #de

【POJ 1258】 Agri-Net

[POJ 1258] Agri-Net 最小生成树模板 Prim #include #define INF 0x3f3f3f3f using namespace std; int mp[501][501]; int dis[501]; bool vis[501]; int n; int Prim() { int i,j,w,p,sum = 0; memset(dis,-1,sizeof(dis)); memset(vis,0,sizeof(vis)); dis[1] = 0; for(i = 0

各种最小生成树。 HDU 1863 HDU 1301 POJ 1258

畅通工程 Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 18811    Accepted Submission(s): 7981 Problem Description 省政府"畅通工程"的目标是使全省任何两个村庄间都可以实现公路交通(但不一定有直接的公路相连,只要能间接通过公路可达即可).经过调查评估,得到的统计表中列出

hdu1301&amp;poj1251 Jungle Roads(最小生成树之prim果题)

转载请注明出处:http://blog.csdn.net/u012860063 题目链接: HDU:http://acm.hdu.edu.cn/showproblem.php?pid=1301 POJ: http://poj.org/problem?id=1251 一道prim算法的果题! 题目很长,这里就不贴题目了. 题意: 给你每个村庄之间的维护道路的费用,求最小的费用. 代码如下: #include <cstdio> #include <cstring> #include &