JAVA实现棋盘覆盖问题

import   java.io.*; 
public class shixi1 {

//static int size=4;
static int tile=0;
static int board[][]=new int[1000][1000];
static void  chessBoard(int tr,int tc,int dr,int dc,int size)
{
if (size == 1) 
return;
    int t = tile++,  
      s = size/2;  
    if (dr < tr + s && dc < tc + s) 
       chessBoard(tr, tc, dr, dc, s);
    else {
       board[tr + s - 1][tc + s - 1] = t;      
       chessBoard(tr, tc, tr+s-1, tc+s-1, s);
       }//左上角  
    if (dr < tr + s && dc >= tc + s)       
       chessBoard(tr, tc+s, dr, dc, s);
    else {     
     board[tr + s - 1][tc + s] = t;   
        chessBoard(tr, tc+s, tr+s-1, tc+s, s);
        }//右上角
     if (dr >= tr + s && dc < tc + s)       
        chessBoard(tr+s, tc, dr, dc, s);
     else {
        board[tr + s][tc + s - 1] = t;      
        chessBoard(tr+s, tc, tr+s, tc+s-1, s);
        }//左下角