答案就是错排数
n = int(input()) f = [0] * 205 f[0] = 1 for i in range(2, n+1): f[i] = (i-1) * (f[i-1] + f[i-2]) print(f[n])
loj2061 「HAOI2016」放棋子
原文：https://www.cnblogs.com/poorpool/p/9001731.html
