POJ 2485Highways (又一个Prim最小生成树水题)

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<queue>
using namespace std;
const int inf=0x3f3f3f3f3f;
const int maxn = 505;
int dis[maxn][maxn];
int ans, n;
int max(int a, int b){
return (a>b)?a:b;
}
void prim(){
int vis[maxn], d[maxn], i, j, k;
memset(vis, 0, sizeof(vis));
memset(d, inf, sizeof(d));
int MIN=inf, v=0;
d[1]=0;
while(true){
MIN = inf , v = -1;
for(i=1; i<=n; i++){
if(!vis[i] && d[i]<MIN){
v = i;
MIN = d[i];
}
}
if(v==-1) return ;
vis[v] = 1;
ans= max(ans,MIN);
for(i=1;i<=n;i++){
if(!vis[i] && d[i] > dis[v][i]){
d[i] = dis[v][i];
}
}
}
return;
}
int main()
{
int T, i, j;
//freopen("in.txt", "r", stdin);
scanf("%d", &T);
while(T--){
memset(dis, 0, sizeof(dis));
ans=0;
scanf("%d", &n);
for(i=1; i<=n; i++){
for(j=1; j<=n; j++){
scanf("%d", &dis[i][j]);
}
}
prim();
printf("%d\n", ans);
}
return 0;

}