poj 1251--Jungle Roads(求最小生成树)

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<string>
 4 #include<cstring>
 5 using namespace std;
 6 
 7 int n;
 8 int dis[30][30];
 9 int minDis[30];
10 int vis[30];
11 
12 int Prim(){
13     int i,j,sum = 0;
14     memset(vis, 0, sizeof(vis));
15     memset(minDis, 0, sizeof(minDis));
16     for (i = 0; i < n; i++)
17         minDis[i] = dis[0][i];//开始集合里只有一个点，大家到集合的距离即为到第一个点的距离
18     vis[0] = 1;
19     int num=n-1,jilu=0;
20     while (num--){
21         int min = 1000;
22         for (i = 0; i < n; i++){
23             if (!vis[i]&&minDis[i] < min){
24                 min = minDis[i];//更新min
25                 jilu = i;
26             }
27         }
28     //    cout <<"加入的点是："<<jilu<< "              sum+的min是：" << min << endl;
29         //if (min!=1000)
30         sum += min;
31         vis[jilu] = 1;//新的jilu点进集合
32         for (j = 0; j < n; j++){//更新点到集合的最短距离
33             if (vis[j])
34                 continue;
35             else if (minDis[j]>dis[jilu][j])
36                 minDis[j] = dis[jilu][j];
37         }
38     }
39 
40     return sum;
41 }
42 
43 int main()
44 {
45     while (cin >> n&&n!=0){
46         int i, j, k, x, y, w, m;
47         char a, b;
48         for (i = 0; i < n; i++)
49             for (j = 0; j < n; j++)
50                 dis[i][j] = dis[j][i] = 1000;
51         for (i = 0; i < n - 1; i++){
52             cin >> a >> m;
53             if (m > 0){
54                 for (j = 0; j < m; j++){
55                     cin >> b >> w;
56                     x = a - ‘A‘;
57                     y = b - ‘A‘;
58                     dis[x][y] = dis[y][x] = w;
59                 }
60             }
61         }
62         cout << Prim() << endl;
63     }
64     return 0;
65 }