Highways (最小生成树）

#include <stdio.h>
#include <string.h>
#include <algorithm>
#define INF 0x3f3f3f3f
using namespace std;
int grid[505][505],dist[505],visit[505],n;
int prime()
{
    int num=1,k,i,ans=0,minc;
    memset (visit,0,sizeof(visit));
    for (i = 1; i <= n; i++)
        dist[i] = grid[1][i];
    visit[1]=1;
    dist[1]=0;
    while(num++<n)
    {
        minc=INF;
        for (i=1;i<=n;i++)
            if(!visit[i] && dist[i]<minc)
            minc=dist[k=i];
        visit[k]=1;
        ans=max(ans,dist[k]);
        for (i=1;i<=n;i++)
            if(!visit[i])
               dist[i]=min(dist[i],grid[k][i]);
    }
    return ans;
}
int main()
{
    int i,j,T;
    scanf("%d",&T);
    while (T--)
    {
        scanf("%d",&n);
        for (i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                scanf("%d",&grid[i][j]);
        printf("%d\n",prime());
    }
	return 0;
}