Wireless Network 并查集

An earthquake takes place in Southeast Asia. The ACM (Asia Cooperated Medical team) have set up a wireless network with the lap computers, but an unexpected aftershock attacked, all computers in the network were all broken. The computers are repaired one by one, and the network gradually began to work again. Because of the hardware restricts, each computer can only directly communicate with the computers that are not farther than d meters from it. But every computer can be regarded as the intermediary of the communication between two other computers, that is to say computer A and computer B can communicate if computer A and computer B can communicate directly or there is a computer C that can communicate with both A and B.

In the process of repairing the network, workers can take two
kinds of operations at every moment, repairing a computer, or testing
if two computers can communicate. Your job is to answer all the testing
operations.

Input

The first line contains two integers N and d (1 <= N <=
1001, 0 <= d <= 20000). Here N is the number of computers, which
are numbered from 1 to N, and D is the maximum distance two computers
can communicate directly. In the next N lines, each contains two
integers xi, yi (0 <= xi, yi <= 10000), which is the coordinate of
N computers. From the (N+1)-th line to the end of input, there are
operations, which are carried out one by one. Each line contains an
operation in one of following two formats:

1. "O p" (1 <= p <= N), which means repairing computer p.

2. "S p q" (1 <= p, q <= N), which means testing whether computer p and q can communicate.

The input will not exceed 300000 lines.

Output

For each Testing operation, print "SUCCESS" if the two computers can communicate, or "FAIL" if not.

Sample Input

4 1
0 1
0 2
0 3
0 4
O 1
O 2
O 4
S 1 4
O 3
S 1 4

Sample Output

FAIL
SUCCESS

遇到这种坐标求距离的最好就是输入double精确度高，然后并查集

代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <string>
#include <cmath>
using namespace std;
int n,d,p,q;
char ch;
int f[];
int stack[],head;
struct loc
{
    double x,y;
    int id;
}ro[];
void init()
{
    for(int i=;i<=n;i++)
        f[i]=i;
}
int getf(int x)
{
    if(x!=f[x])f[x]=getf(f[x]);
    return f[x];
}
int merge(int x,int y)
{
    int xx=getf(x),yy=getf(y);
    f[yy]=xx;
}
void check(int a,int b)
{
    if(sqrt(pow(ro[a].x-ro[b].x,)+pow(ro[a].y-ro[b].y,))<=d)merge(a,b);
}
int main()
{
   scanf("%d %d",&n,&d);
   init();
   for(int i=;i<=n;i++)
   {
       scanf("%lf%lf",&ro[i].x,&ro[i].y);
   }

   while(cin>>ch)
   {
       if(ch=='O')
       {
           scanf("%d",&p);
           stack[head++]=p;
           for(int i=;i<head-;i++)
           {
              check(stack[i],p);
           }
       }
       else
       {
           scanf("%d %d",&p,&q);
           if(getf(p)==getf(q))cout<<"SUCCESS"<<endl;
           else cout<<"FAIL"<<endl;
       }
   }
}