Poj Solution 2488

http://poj.org/problem?id=2488

import java.io.PrintWriter;  
 import java.util.Scanner;  
 import java.util.Stack;  
 public class Main {  
  static class Point{  
   int x ,y;  
   public Point(int x ,int y){  
    this.x = x;  
    this.y = y;  
   }  
  }  

 static int[][] chessboard = new int[27][27];  
  static int num = 1;  
 static int[] DX = {-1,1,-2,2,-2,2,-1,1};  
  static int[] DY = {-2,-2,-1,-1,1,1,2,2};  

  public static void main(String[] args) {  
    Scanner scn = new Scanner(System.in);  
  
   PrintWriter out = new PrintWriter(System.out);  
   int n ,p,q;  
   n = scn.nextInt();  
   int index = 1;  
   while(n-- > 0){  
    p = scn.nextInt();  
    q = scn.nextInt();  
    out.format("Scenario #%d:n%snn", index++,calute(p,q));  
   }  
   out.flush();  
  }  
  static boolean find;//�ҵ���־  
  private static String calute(int p, int q) {  
   //Queue<Point> points = new LinkedList<Point>();  
   Stack<String> result = new Stack<String>();  
   num = 1;  
   find = false;  
   int[][] visited = new int[p][q];  
   result.add("A1");  
   visited[0][0] = 1;  
   bfs(p,q,new Point(0,0),result,visited);  
   if(!find){  
    return "impossible";  
   }  
   return getResult(result);  
  }  
  private static String getResult(Stack<String> result) {  
   StringBuffer sbf = new StringBuffer("");  
   for(String str : result){  
    sbf.append(str);  
   }  
   return sbf.toString();  
  }  
  private static void bfs(int p, int q, Point point, Stack<String> result, int[][] visited) {  
   int x = point.x, y = point.y, nx,ny;  
   if(num == (p*q)){  
    find = true;  
   }  
   for(int i = 0; i < 8 && !find; i++){  
    nx = x + DX[i];  
    ny = y + DY[i];  
       
    if((nx <0 || nx >= p) || (ny < 0 || ny >= q)){  
     continue;  
    }  
    //�ѷ��ʹ�  
    if(visited[nx][ny] == 1){  
     continue;  
    }  
    result.add((char)('A' + ny) + "" + (nx + 1));  
    visited[nx][ny] = 1;  
    num++;  
    bfs(p,q,new Point(nx,ny),result,visited);  
    if(find){  
     break;  
    }  
    visited[nx][ny] = 0;  
    num--;  
    result.pop();  
       
   }  
  }  
    
 }