[并查集] POJ 2236 Wireless Network

#include<stdio.h>
#include<string.h>
#include<math.h>
#define dist(x1,y1,x2,y2) (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)
int father[10050],n,d;
bool ingragh[10050];
struct node
  {
  	 int x,y;
  }node[10050];
int find(int x)
  {
  	 if(x==father[x]) return (x);
  	 else father[x]=find(father[x]);
  	 return (father[x]);
  }
void merge(int x,int y)
  {
  	 int find_x=find(x);
  	 int find_y=find(y);
  	 if(find_x!=find_y&&dist(node[x].x,node[x].y,node[y].x,node[y].y)<=d*d) 
	       father[find_x]=find_y;
  	 return;
  }
void init()
  {
  	 int i;
  	 for(i=1;i<=n;++i) father[i]=i;
  	 memset(ingragh,false,sizeof(ingragh));
  }
int main()
  {
  	 int i,query1,query2;
  	 char c;
  	 scanf("%d%d",&n,&d);
  	 init();
  	 for(i=1;i<=n;++i) scanf("%d%d",&node[i].x,&node[i].y);
	 while(~scanf("%c%d",&c,&query1))
	   {
	   	  if(c==‘O‘) 
			 {
			    for(i=1;i<=n;++i) if(ingragh[i]) merge(i,query1);
			    ingragh[query1]=true;
		     }
		  else
	   	  if(c==‘S‘)
	   	    {
	   	  	   scanf("%d",&query2);
	   	  	   if(ingragh[query1]&&ingragh[query2])
	   	  	     {
				    if(find(query1)==find(query2)) 
					   {
					     printf("SUCCESS\n");
				         continue;
				       }
			     } 
			   printf("FAIL\n");
		    }
	   }
  	 return 0;
  }