poj 2236 Wireless Network 并查集

#include <stdio.h>
#include <string.h>
#include <math.h>
#define maxn 1220
double x[maxn],y[maxn],d;
bool vis[maxn];
int p[maxn];
int n;
double dist(int i,int j)
{
    return fabs( (x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]) );
}
int find(int x)
{
    if(x==p[x]) return p[x];
    return p[x]=find(p[x]);
}
void link(int a,int b)
{
    int fa=find(a);
    int fb=find(b);
    if(fa!=fb)
        p[fa]=fb;
}
int main()
{
    int i;
    int u,v;
    scanf("%d%lf",&n,&d);
    for(i=1;i<=n;i++)
    {
        scanf("%lf%lf",&x[i],&y[i]);
        p[i]=i;
        vis[i]=0;
    }
    char op;
    getchar();
    while(scanf("%c",&op)!=EOF)
    {
        if(op=='O')
        {
            scanf("%d",&u);
            vis[u]=1;
            for(i=1;i<=n;i++)
                if(vis[i]&&i!=u&&dist(i,u)<=d*d)
                    link(i,u);
        }
        else
        {
            scanf("%d%d",&u,&v);
            int fu=find(u);
            int fv=find(v);
            if(fu!=fv) printf("FAIL
");
            else printf("SUCCESS
");
        }
        getchar();
    }
    return 0;
}