poj-2236

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并查集：

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <sstream>
#include <stdlib.h>
#include <malloc.h>

using namespace std;

int n,t;

struct pp
{
    int x;
    int y;
}p[10000];

int makedis(pp a,pp b)//计算两点距离
{
    return (double (a.x*1.0-b.x*1.0)*(a.x*1.0-b.x*1.0)+(a.y*1.0-b.y*1.0)*(a.y*1.0-b.y*1.0) );
}

int ran[10000];
int qq[10000];
int pq[10000];

int findd (int x)
{
    if (x == pq[x])
        return x;
    else
        return pq[x]=findd(pq[x]);
}

int un(int a,int b)
{
    int fa = findd(a);
    int fb = findd(b);
    if (fa == fb )
        return 0;
    else
    {
        if (ran[fa]>ran[fb])
        {
            pq[fb]=fa;
        }
        else
        {
            pq[fa]=fb;
            if (fa==fb)
                ran[fa]++;
        }
    }
}

int main ()
{
    int n,d;
    while (cin>>n>>d)
    {
        memset(ran,0,sizeof(ran));
        memset(qq,0,sizeof(qq));
        memset(pq,0,sizeof(pq));

        for (int i=1;i<=n;i++)
        {
            cin>>p[i].x>>p[i].y;
            pq[i]=i;
        }

        char q[5];
        int x,y;
        while (cin>>q)
        {
            if (!strcmp(q,"O"))
            {
                cin>>x;
                qq[x]=1;
                for (int i=1;i<=n;i++)
                {
                    if (makedis(p[i],p[x])<=d*d && qq[i] && i!=x &&(  findd(x)!=findd(i) ))
                    {
                        un(i,x);
                    }
                }
            }
            else if (!strcmp(q,"S"))
            {
                cin>>x>>y;
                if (findd(x)==findd(y))
                    printf("SUCCESS\n");
                else
                    printf("FAIL\n");
            }
        }
    }
    return 0;
}