[算法]机器人运动范围

public class Solution {
     public int movingCount(int threshold, int rows, int cols) {
        boolean[][] flag = new boolean[rows][cols];
        return movingCount(threshold, rows, cols, 0, 0, flag);
    }

    private int movingCount(int threshold, int rows, int cols, int i, int j, boolean[][] flag){
        if(i < 0 || i >= rows || j < 0 || j >= cols || getSum(i) + getSum(j) > threshold || flag[i][j] == true){
            return 0;
        }
        flag[i][j] = true;
        return movingCount(threshold, rows, cols, i - 1, j, flag) +
                movingCount(threshold, rows, cols, i + 1, j, flag) +
                movingCount(threshold, rows, cols, i, j - 1, flag) +
                movingCount(threshold, rows, cols, i, j + 1, flag) + 1;
    }

    private int getSum(int num){
        if(num == 0){
            return 0;
        }else{
            return num % 10 + getSum(num / 10);
        }
    }
}