（最小生成树）QS Network -- ZOJ --1586

链接：

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=1586

http://acm.hust.edu.cn/vjudge/contest/view.action?cid=82831#problem/E

代码：

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

const int N = 1000;
const int INF = 0xfffffff;

int n;
int J[N][N], dist[N];
bool vis[N];

int Prim()
{
    int i, j, ans=0;
    dist[1]=0;
    memset(vis, 0, sizeof(vis));
    vis[1]=1;

    for(i=1; i<=n; i++)
        dist[i]=J[1][i];

    for(i=1; i<n; i++)
    {
        int index=1;
        int MIN=INF;
        for(j=1; j<=n; j++)
        {
            if(!vis[j] && dist[j]<MIN && dist[j])
            {
                index=j;
                MIN=dist[j];
            }
        }
        vis[index]=1;
        ans += MIN;
        for(j=1; j<=n; j++)
        {
            if(!vis[j] && dist[j]>J[index][j])
                dist[j]=J[index][j];
        }
    }
    return ans;
}

int main ()
{
    int t;
   scanf("%d", &t);
    while(t--)
    {
        int i, j, a, b[N];
        scanf("%d", &n);

        memset(J, 0, sizeof(J));
        memset(b, 0, sizeof(b));

        for(i=1; i<=n; i++)
        {
            scanf("%d", &a);
            b[i] = a;
        }

        for(i=1; i<=n; i++)
        for(j=1; j<=n; j++)
        {
            scanf("%d", &a);
            J[i][j] = a;
        }

        for(i=1; i<=n; i++)
        {
            for(j=1; j<=n; j++)
            J[i][j] += b[i]+b[j];
        }

        int ans=Prim();

        printf("%d\n", ans);
    }
    return 0;
}