用DFS解决迷宫寻路问题的时间与空间复杂度

Question

一个二维迷宫，判断一个人是否能从（0，0）要走到某个值为9的点，迷宫用2D数组表示，1为路，0为墙。请问以下代码的时间复杂度和空间复杂度？我有点绕晕了算不出来，谢谢！

 public boolean find(int[][] grid){
    if(grid==null || grid.length==0 || grid[0].length==0 || grid[0][0]==0) return 0;
    return helper(grid,0,0);    
}
private boolean helper(int[][] grid,int x, int y){
    if(x>=0&&x<grid.length&&y>=0&y<grid[0].length){
        if(grid[x][y]==0) return false;
        else if(grid[x][y]==9) return true;
        else if(grid[x][y]==1){
            grid[x][y]=2;
            return helper(grid,x,y-1)||helper(grid,x+1,y)||helper(grid,x,y+1)||helper(grid,x-1,y);
        }
        else return false;
    }
    else return false;
}

Answer 1

http://blog.csdn.net/achiberx/article/details/8068080