(并查集模板题)Wireless Network POJ - 2236

#include <iostream>
#include <algorithm>
#include <string.h>
#include <cstdio>
#include <string>
#include <cmath>
#include <vector>
#include <stack>
#include <queue>
#include <stack>
#include <list>
#include <map>
#include <set>
//#include <unordered_map>
#define Fbo friend bool operator < (node a, node b)
#define mem(a, b) memset(a, b, sizeof(a))
#define FOR(a, b, c) for (int a = b; a <= c; a++)
#define RFOR(a, b, c) for (int a = b; a >= c; a--)
#define off ios::sync_with_stdio(0)
#define sc(a) scanf("%d",&a) 
bool check1(int a) { return (a & (a - 1)) == 0 ? true : false; }

using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const int Maxn = 1e5 + 5;
const double pi = acos(-1.0);
const double eps = 1e-8;

int a[Maxn],n,d;
int b[Maxn], cnt=0;//被修理的电脑编号
bool vis[Maxn];

struct node {
	int x, y;
}point[Maxn];

void init() {
	for (int i = 1; i < Maxn; i++)
		a[i] = i;
}

int find(int x) {
	return x == a[x] ? x : find(a[x]);
}

void unite(int x, int y) {
	x = find(x);
	y = find(y);
	if (x != y) {
		a[x] = a[y];
	}
}

bool check(int a, int b) {
	double dis = sqrt((double)((point[a].x - point[b].x) * (point[a].x - point[b].x)) + ((point[a].y - point[b].y) * (point[a].y - point[b].y)));
	//cout << dis << "---" << d << endl;
	return dis <= d;
}

int main() {
	off;
	mem(vis, 0);
	cin >> n >> d;
	init();
	for (int i = 1; i <= n; i++) {
		cin >> point[i].x >> point[i].y;
	}
	char ch;
	while (cin >> ch) {
		if (ch == ‘O‘) {
			int m;
			cin >> m;
			vis[m] = 1;
			for (int i = 0; i < cnt; i++) {
				if (check(b[i], m)) {
					unite(b[i], m);
				}
			}
			b[cnt++] = m;
		}
		else {
			int l, r;
			cin >> l >> r;
			if (vis[l] && vis[r] && find(l) == find(r)) {
				cout << "SUCCESS" << endl;
			}
			else cout << "FAIL" << endl;
		}
	}
	return 0;
}