nyoj 38 布线问题

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=38

最小生成树水题~

代码：

#include "stdio.h"  // 最小生成树 Kruskal
#include "string.h"
#include "stdlib.h"

#define N 505
#define INF 0x3fffffff
int set[N];

int find(int x){ return set[x]==x?x:find(set[x]); }

void Init(int n){ for(int i=1; i<=n; ++i) set[i]=i; }

struct node
{
    int x,y;
    int cost;
}p[N*N];

int cmp(const void *a,const void *b)
{
    node *c = (node *)a;
    node *d = (node *)b;
    return c->cost - d->cost;
}

int main()
{
    int T;
    int n,m;
    int i,k;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d %d",&n,&m);
        for(i=0; i<m; ++i)
            scanf("%d%d%d",&p[i].x,&p[i].y,&p[i].cost);
        qsort(p,m,sizeof(p[0]),cmp);
        int ans = INF;
        for(i=0; i<n; ++i)
        {
            scanf("%d",&k);
            ans = ans<k?ans:k;
        }
        Init(n);
        int fa,fb;

        for(i=0; i<m; ++i)
        {
            fa = find(p[i].x);
            fb = find(p[i].y);
            if(fa==fb) continue;
            ans += p[i].cost;
            if(fa>fb)
                set[fa] = fb;
            else
                set[fb] = fa;
        }
        printf("%d\n",ans);
    }
    return 0;
}