提交时间:2021-04-03 14:05:58
运行 ID: 6546
#include <bits/stdc++.h> using namespace std; const int MAXN = 1008; int a[MAXN] = {1, 1, 0, 0}; int n, mod; int main() { while(cin >> n >> mod) { for(int i = 4; i <= n; i++) { a[i] = (((i + 1) * a[i - 1] % mod - (i - 2) * a[i - 2] % mod - (i - 5) * a[i - 3] % mod + (i - 3) * a[i - 4] % mod) % mod + mod) % mod; } cout << a[n] % mod << endl; } return 0; }