POJ 2236 Wireless Network 几何+并查集

浏览数：17 / 时间：2015年06月09日

Wireless Network

Time Limit: 10000MS		Memory Limit: 65536K
Total Submissions: 14794		Accepted: 6227

Description

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

Sample Output

FAIL
SUCCESS

Source

POJ Monthly,HQM

有n台坏了电脑，知道它们的坐标，并且如果两台之间的距离小于d的话，并且这两台都修好了就可以联网，并且可以通过其它电脑连接。

简单并查集。

//4340K	3079MS
#include<stdio.h>
#include<string.h>
#include<math.h>
#define M 1007
char s[5];
int x[M],y[M],pre[M],vis[M],g[M][M];
int n,d;
void init()
{
    memset(g,0,sizeof(g));
    for(int i=1;i<=n;i++)
    {
        pre[i]=i;
        vis[i]=0;
    }
        
}
int find(int x)
{
    while(x!=pre[x])
        x=pre[x];
    return x;
}
bool judge(int i,int j)
{
    return ((y[j]-y[i])*(y[j]-y[i])+(x[j]-x[i])*(x[j]-x[i]))<=d*d;
}
int main()
{
    scanf("%d%d",&n,&d);
    init();
    int a,b,c;
    for(int i=1;i<=n;i++)
        scanf("%d%d",&x[i],&y[i]);
    while(scanf("%s",s)!=EOF)
    {
        if(s[0]==‘O‘)
        {
            scanf("%d",&c);
            vis[c]=1;
            for(int i=1;i<=n;i++)
            {
                if(i==c)continue;
                if(judge(c,i)&&vis[i])
                {
                    int xx=find(c);
                    int yy=find(i);
                    pre[xx]=yy;
                }
            }
        }
        if(s[0]==‘S‘)
        {
            scanf("%d%d",&a,&b);
            if(find(a)==find(b))printf("SUCCESS\n");
            else printf("FAIL\n");
        }
    }
    return 0;
}

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POJ 2236 Wireless Network 几何+并查集