Poj Solution 1522

http://poj.org/problem?id=1522

/* @author:zeropinzuo */
import java.io.*;
import java.util.*;

public class Main{
 static Scanner cin;
 static int count=0;
 public static void main(String args[]){
  cin = new Scanner(System.in);
  int n;
  while((n=cin.nextInt())!=0)
   run(n);
  }
    
 static void run(int n){
   Point start,end;
   start = new Point(n, cin);
   end   = new Point(n, cin);
        
   ArrayList< PointSet> Mset = new ArrayList< PointSet>();
        
   PointSet startSet = new PointSet();
   PointSet endSet = new PointSet();
   startSet.add(start);
   endSet.add(end);
    
   Mset.add(startSet);
   Mset.add(endSet);
        
   Point A,B;
   PointSet setA=new PointSet(), setB=new PointSet();
   while(true){
    if(cin.hasNext("-1") == true){
     cin.nextInt();
     break;
    }
                
    setA = null;
    setB = null;
    A = new Point(n, cin);
    B = new Point(n, cin);
            
    for(PointSet set:Mset){
    if(set.contains(A))
      setA = set;
    if(set.contains(B))
      setB = set;
    }
            
   if((setA != null)&&(setB != null)){
    if(setA != setB){
    setA.addAll(setB);
    Mset.remove(setB);
    }    
   }
   else if(setA != null)
    setA.add(B);
   else if(setB != null)
    setB.add(A);
   else{
    setA = new PointSet();
    setA.add(A);
    setA.add(B);
    Mset.add(setA);
   }
                                        
 }
        
 startSet = null;
 endSet   = null;
 for(PointSet set:Mset){
  if(set.contains(start))
    startSet = set;
  if(set.contains(end))
    endSet = set;
  }
        
  if(startSet == endSet)
    System.out.println("Maze #"+(++count)+" can be travelled");
  else
    System.out.println("Maze #"+(++count)+" cannot be travelled");
 }
}

class Point implements Comparable{
 int num;
        
 public Point(int n, Scanner cin){
   num=0;
 for(int i=0;i< n;i++)
  num = 10*num+cin.nextInt();
}
    
 public int compareTo(Object another){
   Point p = (Point)another;
    
   return this.num-p.num;
 }
}

class PointSet extends TreeSet< Point>{
    
}