Constructing Roads----poj2421

题目链接：

http://poj.org/problem?id=2421

想把n个村庄连接在一起；求最小生成树，不同的是已经有了m条线段链接在一起了，求剩下的；

感觉用Kruskal会简单一点

#include<stdio.h>

#include<string.h>

#include<map>

#include<iostream>

#include<algorithm>

#include<math.h>

#define N 110

#define INF 0xfffffff



using namespace std;



int f[N];



struct node

{

    int x,y,d;

}a[N*N];



int cmp(node p,node q)

{

    return p.d < q.d;

}



int Find(int x)

{

    if(x!=f[x])

        f[x]=Find(f[x]);

    return f[x];

}



int main()

{

    int n, i, j, k, m, d, x, y, px, py, ans;

    while(scanf("%d",&n)!=EOF)

    {

        memset(a, 0, sizeof(a));

        k = ans = 0;

        for(i=0;i<=n;i++)

            f[i]=i;

        for(i=1; i<=n; i++)

            for(j=1; j<=n; j++)

            {

                scanf("%d",&d);

                if(i<j)

                    a[k].x = i, a[k].y = j, a[k++].d = d;

            }

        sort(a,a+k,cmp);

        scanf("%d", &m);

        for(i=0; i<m; i++)

        {

            scanf("%d%d", &x, &y);

            px = Find(x);

            py = Find(y);

            if(px != py)

                f[px] = py;

        }

        for(i=0; i<k; i++)

        {

            px = Find(a[i].x);

            py = Find(a[i].y);

            if(px != py)

                f[px] = py,ans+=a[i].d;

        }

        printf("%d\n",ans);

    }

    return 0;

}