JAVA 代码

class Solution {
    static int steps = 0;
    static int[] dx = {-1, 0, 1, 0};
    static int[] dy = {0, 1, 0, -1};
    static class Point{
        int x,y;

        public Point(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }

    public static int movingCount(int threshold, int rows, int cols) {
        if (rows <= 0 || cols <= 0){
            return 0;
        }
        int[][] book = new int[rows + 1][cols + 1];
        Queue<Point> queue = new LinkedList<>();
        queue.add(new Point(0,0));
        steps++;
        book[0][0] = 1;
        while (!queue.isEmpty()){
            Point p = queue.poll();
            if (p != null){
                for (int i = 0; i < 4; i++) {
                    int x = p.x + dx[i];
                    int y = p.y + dy[i];
                    // 满足条件才加进队列
                    if (x >= 0 && x < rows && y >=0 && y< cols && reachable(x,y,threshold,book)){
                        queue.add(new Point(x,y));
                        book[x][y] = 1;
                        steps++;
                    }
                }
            }
        }
        return steps;
    }


    private static boolean reachable(int x, int y, int threshold, int[][] book){
        if (book[x][y] == 1){
            return false;
        }
        while (x > 0){
            threshold -= x %10;
            x /= 10;
        }
        while (y > 0){
            threshold -= y%10;
            y /= 10;
        }
        return threshold >= 0;
    }
}