sicily 1090 Highways

求最小生成树的长度最小的边，我用的是prim算法:

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int INF=0x3f3f3f3f;
int map[505][505];
int visit[505];
int dis[505];
int ans[505];

//最小生成树 
int prim(int n, int cur) //从哪个点开始都可以 
{
    memset(ans, 0, sizeof(ans));
    visit[cur] = 1;
    int index;
    int count=0;
    for(int i=1; i<=n; i++)
        dis[i] = map[cur][i]; //dis[i]为到每个相邻顶点的最小距离 
    
    for(int i=2; i<=n; i++)
    {
        int minn = 0x3f3f3f3f;
        for(int j=1; j<=n; j++)
        {
            if(!visit[j] && dis[j] < minn)
            {
                minn = dis[j];
                index = j;
            } 
        }
        visit[index] = 1;
        ans[count++] = minn;
        
        for(int j=1; j<=n; j++)
            if(!visit[j] && dis[j] > map[index][j])
                dis[j] = map[index][j];
    }
    return count;
}

int main()
{
    int t, n;
    scanf("%d", &t);
    int k=0;
    while(t--)
    {
        if(k==0)
            k++;
        else
            printf("
");
        memset(dis, 0, sizeof(dis));
        memset(map, 0, sizeof(map));
        memset(visit, 0, sizeof(visit));
        
        scanf("%d", &n);
        for(int i=1; i<=n; i++)
            for(int j=1; j<=n; j++)
            {
                map[i][j] = INF; 
                scanf("%d", &map[i][j]);
            }
        int cnt = prim(n, 1);
        sort(ans, ans+cnt);
        printf("%d
", ans[cnt-1]);
    }
    return 0;
}