hdu4463 Outlets 最小生成树

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4463

很裸的一道题目，稍微处理一下输入即可

代码：

 #include<iostream>
 #include<cstdlib>
 #include<cstdio>
 #include<cstring>
 #include<cmath>
 #include<algorithm>
 using namespace std;
 #define maxn 60
 int n;
 double sumweight;
 int tol;
 int cnt;
 int p,q;
 class node
 {
   public:
   int from;
   int to;
   double w;
 };
 class point
 {
    public:
    int x;
    int y;
 };
 point address[maxn];
 node edge[maxn*maxn];
 int  parent[maxn*maxn];
 double dis(point a,point b)
 {
     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
 }
 void addEdge(int u,int v)
 {
    edge[tol].from=u;
    edge[tol].to=v;
    edge[tol].w=dis(address[u],address[v]);
    if((u==p && v==q)||(u==q && v==p))
    edge[tol].w=;
    tol++;
 }
 void UFset()
 {
    for(int i=;i<maxn*maxn;i++)
        parent[i]=-;
 }
 int Find(int x)
 {
    int s;
     for(s=x;parent[s]>=;s=parent[s]);//我总是把parent[s]>=0 写为s>=0;
     while(s!=x)
     {
         int tmp=parent[x];
         parent[x]=s;
         x=tmp;
     }

    return s;
 }
 void Union(int u,int v)
 {
     int r1=Find(u);
     int r2=Find(v);
     int tmp=parent[r1]+parent[r2];
     if(parent[r1]>parent[r2])
     {
         parent[r1]=r2;
         parent[r2]=tmp;
     }
     else
     {
         parent[r2]=r1;
         parent[r1]=tmp;
     }
 }
 bool cmp(node a ,node b)
 {
      return a.w < b.w;
 }
 void Kruskal()
 {
     int u,v;
     UFset();
     cnt=;
    for(int i=;i<tol;i++)
    {
        u=edge[i].from;
        v=edge[i].to;
        if(Find(u)!= Find(v))
        {
             sumweight+=edge[i].w;
             cnt++;
             Union(u,v);
             if(cnt==n-) break;
        }
    }

 }
 int main()
 {
      while(scanf("%d",&n)&&n)
      {
         tol=;

         scanf("%d%d",&p,&q);
         int x,y;
         for(int i=;i<=n;i++)
          {
             scanf("%d%d",&x,&y);
             address[i].x=x;
             address[i].y=y;
          }
         for(int i=;i<=n;i++)
          for(int j=i+;j<=n;j++)
             {
                addEdge(i,j);
             }
         sumweight=dis(address[p],address[q]);
         sort(edge,edge+tol,cmp);
         Kruskal();
         printf("%.2f\n",sumweight);

     }

    return ;
 }