public class Maze {
    private final int tried = 3;
    private final int path = 7;
    
    private int[][] grid = { {1,1,1,0,1,1,0,0,0,1,1,1,1},
			     {1,0,1,1,1,0,1,1,1,1,0,0,1},
			     {0,0,0,0,1,0,1,0,1,0,1,0,0},
			     {1,1,1,0,1,1,1,0,1,0,1,1,1},
			     {1,0,1,0,0,0,0,1,1,1,0,0,1},
			     {1,0,1,1,1,1,1,1,0,1,1,1,1},
			     {1,0,0,0,0,0,0,0,0,0,0,0,0},
			     {1,1,1,1,1,1,1,1,1,1,1,1,1} };

    public boolean traverse(int row, int col) {
	boolean done = false;
	
	if (valid(row, col)) {
	    grid[row][col] = tried; // we've visited this cell
	    
	    if (row == grid.length - 1 && col == grid[0].length -1) {
		// we're in the lower right - done!
		done = true;
	    } else {
		done = traverse(row+1, col); //try to move down
		if (!done)
		    done = traverse(row, col+1); // try to move right
		if (!done)
		    done = traverse(row-1, col); // try to move left
		if (!done)
		    done = traverse(row, col-1); // try to move up
	    }
	    if (done) // this cell is part if the solution
		grid[row][col] = path;
	}
	return done;
    }

    public boolean valid(int row, int col) {
	boolean result = false;
	// are we inside the matrix?
	if (row >= 0 && row < grid.length && col >= 0 && 
	    col < grid[row].length) {
	    // Is the cell either blocked or previously tried?
	    if (grid[row][col] == 1) {
		result = true;
	    } 
	}
	return result;
    }
    
    public String toString() {
	String result = "\n";
	for (int row = 0; row < grid.length; row++) {
	    for (int col = 0; col < grid[row].length; col++) {
		result += grid[row][col] + " ";
	    }
	    result += "\n";
	}
	return result;
    }
}