HDU1301-Jungle Roads

http://acm.hdu.edu.cn/showproblem.php?pid=1301

#include<iostream>
#include<cstdio>
#include<cstring>
#define INF 0xfffffff
int map[28][28],f[133],n,vis[28],dis[28],min;
void prim()
{
    int i,j,k,ans=0;
    memset(vis,0,sizeof(vis));
    for(i=1;i<=n;i++)
       dis[i]=map[1][i];
    vis[1]=1;
    for(i=1;i<n;i++)
    {
        min=INF;
        for(j=1;j<=n;j++)
        if(!vis[j]&&dis[j]<min)
        {
            min=dis[j];
            k=j;
        }
        vis[k]=1;
        ans+=min;
        for(j=1;j<=n;j++)
           if(!vis[j]&&dis[j]>map[k][j])
              dis[j]=map[k][j];
     }
     printf("%d\n",ans);
}
int main(void)
{
    int i,j,m,d;
    char s,c;
    for(i='A';i<='Z';i++)
       f[i]=i-'A'+1;
    while(scanf("%d",&n),n)
    {
        for(i=1;i<=n;i++)
           for(j=1;j<=n;j++)
              map[i][j]=INF;
        getchar();
        for(i=1;i<n;i++)
        {
           scanf("%c%d",&s,&m);
           getchar();
           while(m--)
           {
                  scanf("%c%d",&c,&d);
               getchar();
               map[f[s]][f[c]]=map[f[c]][f[s]]=d;
           }
        }
        prim();
    }
    return 0;
}