F - Wireless Network 暴力更新+并查集

#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstdlib>
#include <cstring>
#define _for(i,a,b) for(int i= a;i<b;i++)
using namespace std;
const int N = 1e3+5;
typedef long long ll;
int flag[N],f[N];
int n,d;
struct Node{
    int x,y;
}a[N];
int find( int x ){
    if( f[x]==x ) return x;
    return f[x]=find( f[x] );
}
int merge(int x,int y){
    if( find(x)!= find(y) ){
        f[find(x)] = find(y);
    }
}
inline double dis(int x1,int y1,int x2,int y2){
    return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) );
}
int main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin>>n>>d;
    _for(i,1,n+1) cin>>a[i].x>>a[i].y , f[i]=i;
    char c;
    while(cin>>c){
        int j,k;
        if(c==‘O‘){
            cin>>j;
            flag[j] = 1;
            _for(i,1,n+1){
                if( i == j) continue;
                if(flag[i]  && dis( a[i].x,a[i].y,a[j].x,a[j].y ) <= d ){
                    merge( i,j );
                }
            }
        }else if( c==‘S‘){
            cin>>j>>k;
            if( flag[j] && flag[k] &&find(j)==find(k) ){
                cout<<"SUCCESS"<<endl; 
            }
            else cout<<"FAIL"<<endl;
        }
    }
    return 0;
}