题解 | #机器人的运动范围#

public class Solution {
    public int movingCount(int threshold, int rows, int cols) {
        if (threshold == 0) {
            return 1;
        }
        int[][] sign = new int[rows][cols];
        return process(0, 0, rows, cols, threshold, sign);
    }
    public static int process(int x, int y, int m, int n, int k, int[][] sign) {
        if (x < 0 || x >= m || y < 0 || y >= n || sign[x][y] == 1 || !isValid(x, y, k)) {
            return 0;
        }
        sign[x][y] = 1;
        return 1 + process(x - 1, y, m, n, k, sign) + process(x + 1, y, m, n, k, sign) + process(x, y - 1, m, n, k, sign) + process(x, y + 1, m, n, k, sign);
    }
    public static boolean isValid(int x, int y, int k) {
        int sum = 0;
        while (x != 0 && y != 0) {
            sum += x % 10 + y % 10;
            x /= 10;
            y /= 10;
        }
        while (x != 0) {
            sum += x % 10;
            x /= 10;
        }
        while (y != 0) {
            sum += y % 10;
            y /= 10;
        }
        return sum <= k ? true : false;
    }
}