POJ2485 最小生成树

 1 //Memory: 532K        Time: 172MS
 2 #include <iostream>
 3 #include <cstring>
 4 #include <string>
 5 #include <algorithm>
 6 
 7 const int maxn = 501;
 8 int g[maxn][maxn];
 9 bool vis[maxn];
10 int d[maxn];
11 int n, t; 
12 int _min, _max;
13 
14 void prim()
15 {
16     memset(vis, 0, sizeof(vis));
17     vis[0] = 1;
18     int size = 1;
19     _max = 0;
20     for (int i = 1 ; i < n; i++){
21         d[i] = g[0][i];
22     }
23     while (size < n) {
24         _min = 65536;
25         int k;
26         for (int i = 1; i < n; i++) {
27             if ( !vis[i] && d[i] < _min) {
28                 _min = d[i];
29                 k = i;
30             }
31         } 
32         vis[k] = 1;
33         if (_min > _max) _max = _min;
34 
35         for (int i = 0; i < n; i++) {
36             if ( !vis[i] && g[i][k] < d[i])
37                 d[i] = g[k][i];
38         }
39         size++;
40     }
41 }
42 
43 int main()
44 {
45     scanf("%d", &t);
46     while (t--){
47         scanf("%d", &n);
48         for (int i = 0; i < n; i++)
49             for (int j = 0; j < n; j++)
50                 scanf("%d", &g[i][j]);
51         prim();
52         printf("%d\n", _max);
53     }
54     return 0;
55 }