# POJ 1258 Agri-Net C语言版 Kruskal

POJ题解 4011浏览

Kruskal算法的应用

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

Slyar:简单介绍一下题意。农民要建立互联网络，目的使村庄里所有的农民连上网，并且总费用最小。多组数据，每组数据给出一个n，然后给出n * n大小的无向图的邻接矩阵表示，值表示边权。要求输出最小生成树的权值和。

### 网友最新评论 (2)

1. @Rve 哇 可以获取到g+头像， 好厉害的样子
Rve10年前（2012-06-24）回复
2. printf("%dn", sum); \\ \貌似被吃掉了.. 代码高亮的问题？
Rve10年前（2012-06-24）回复