Wireless Network

题目链接:http://poj.org/problem?id=2236

注意:题目中说的是 1~n,所以,在初始化根节点的时候不要弄成 0 ~ n-1这种(for(int i = 0;i < n;i++) 这种是不对的,如果这样,则造成n没有对应的根节点,因为初始化的时候根本没有初始化到n

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
using namespace std;

const int maxn = 1010;

struct node {
    int x,y;
    bool open;
}arr[maxn];
int f[maxn];
int n,d;

void Init(int n) {
    for(int i = 1;i <= n;i++)
        f[i] = i;
}

int FindRoot(int x) {
    if(x == f[x])
        return x;
    f[x] = FindRoot(f[x]);
    return f[x];
}

double Count(node a,node b) {
    return sqrt(pow(a.x - b.x,2) + pow(a.y - b.y,2));
}

void Union(int x) {
    int a = FindRoot(x);
    for(int i = 1;i <= n;i++) {
        int b = FindRoot(i);
        if(arr[i].open && Count(arr[i],arr[x]) <= d)
            f[b] = a;
    }
}

int main() {
    while(scanf("%d%d",&n,&d) != EOF) {
        Init(n);
        for(int i = 1;i <= n;i++) {
            scanf("%d%d",&arr[i].x,&arr[i].y);
            arr[i].open = false;
        }
        char ch;
        int x,y;
        while(cin>>ch) {
            if(ch == 'O') {
                scanf("%d",&x);
                arr[x].open = true;
                Union(x);
            }
            else {
                scanf("%d%d",&x,&y);
                if(FindRoot(x) == FindRoot(y))
                    printf("SUCCESS\n");
                else
                    printf("FAIL\n");
            }
        }
    }
    return 0;
}