题目：
题解：
class Solution:def countArrangement(self, n: int) -> int:f = [0] * (1 << n)f[0] = 1for mask in range(1, 1 << n):num = bin(mask).count("1")for i in range(n):if mask & (1 << i) and (num % (i + 1) == 0 or (i + 1) % num == 0):f[mask] += f[mask ^ (1 << i)]return f[(1 << n) - 1]
