poj 2236 （并查集）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
using namespace std;
#define MAXN 1010
int mark[MAXN];
int  dis[MAXN][MAXN];
int  x[MAXN],y[MAXN];
int father[MAXN];
char c[100];
int find_set(int a)
{
    if(a==father[a])return a;
    return father[a]=find_set(father[a]);
}
void union_set(int a,int b)
{
    int ra=find_set(a);
    int rb=find_set(b);
    father[ra]=rb;
}
int main()
{
    int n,d,i,j,ra,rb,a,b;
    scanf("%d%d",&n,&d);
    d=d*d;
    for(i=1;i<=n;i++)
        scanf("%d%d",&x[i],&y[i]);

    for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
            if(((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]))<=d)
                dis[i][j]=dis[j][i]=1;
    for(i=1;i<=n;i++)
        father[i]=i;
    while(scanf("%s",c)!=EOF)
    {
        if(c[0]=='O')
        {
            scanf("%d",&a);
            ra=find_set(a);
            mark[a]=1;
            for(i=1;i<=n;i++)
            {
                rb=find_set(i);
                if(dis[a][i]==1&&rb!=ra&&mark[i]==1)
                    union_set(ra,rb);
            }        
        }
        else 
        {
            scanf("%d%d",&a,&b);
            ra=find_set(a);
            rb=find_set(b);
            if(ra!=rb)
                printf("FAIL\n");
            else 
                printf("SUCCESS\n");
        }
    }
    return 0;
}