线性dp-计数类题目11(不等数列)

AC Code

#include <bits/stdc++.h>
using namespace std;
#define int long long
int n, k, f[1005][1005];

signed main() {
	cin >> n >> k;
	f[1][0] = 1;
	for (int i = 1; i <= n - 1; i++) {
		for (int j = 0; j < i; j++) {
			f[i + 1][j] = (f[i + 1][j] + f[i][j] * (j + 1) % 2015) % 2015;
			f[i + 1][j + 1] = (f[i + 1][j + 1] + f[i][j] * (i - j) % 2015) % 2015;
		}
	}
	cout << f[n][k];
	return 0;
}