Highways(prim)

http://poj.org/problem?id=2485

此题是求最小生成树里的最大权值。prim算法：

 #include<stdio.h>
 #include<string.h>
 const int maxn=;
 const int INF = <<;
 int map[maxn][maxn];
 int dis[maxn],vis[maxn];
 int n,maxm;
 void prim()
 {
     int pos;
     for (int i = ; i <= n; i ++)
     {
         dis[i] = map[][i];
     }
     vis[] = ;
     for (int i = ; i <= n-; i ++)
     {
         int min = INF;
         for (int j = ; j <= n; j ++)
         {
             if (!vis[j] && dis[j] < min)
             {
                 min = dis[j];
                 pos = j;
             }
         }
         if(min > maxm)
         {
             maxm = min;
         }
         vis[pos] = ;
         for (int j = ; j <= n; j ++)
         {
             if (!vis[j] && dis[j] > map[pos][j])
                 dis[j] = map[pos][j];
         }
     }
 }
 void init()
 {
     maxm = -;
     for (int i = ; i <= n; i ++)
     {
         for (int j = ; j <= n; j ++)
         {
             map[i][j] = INF;
         }
         map[i][i] = ;
         vis[i] = ;
     }
 }
 int main()
 {
     int t;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d",&n);
         init();
         for (int i = ; i <= n; i ++)
         {
             for (int j = ; j <= n; j ++)
             {
                 scanf("%d",&map[i][j]);
             }
         }
         prim();
         printf("%d\n",maxm);
     }
     return ;
 }