Lähetit

#include <iostream>

#define ll long long
#define M 1000000007

using namespace std;

ll n, k;
ll bl[101][101], wh[102][101];

int main() {
	cin >> n >> k;
	bl[0][0] = 1;
	for (ll i=1;i<=n;i+=2) {
		bl[i][0] = 1;
		ll tmp = 2;
		if (i == n) tmp = 1;
		for (ll j=1;j<=n;j++) {
			bl[i][j] = bl[i-1][j];
			bl[i][j] += bl[i-1][j-1]*tmp*(i-j+1);
			bl[i][j] %= M;
			if (j<2) continue;
			bl[i][j] += 
bl[i-1][j-2]*(tmp/2)*(i-j+2)*(tmp-1)*(i-j+1);
			bl[i][j] %= M;
		}
		for (int j=0;j<=n;j++) {
			bl[i+1][j] = bl[i][j];
		}
	}
	wh[1][0] = 1;
	for (ll i=2;i<=n;i+=2) {
		wh[i][0] = 1;
		ll tmp =2;
		if (i == n) tmp = 1;
		for (ll j=1;j<=n;j++) {
			wh[i][j] = wh[i-1][j];
			wh[i][j] += wh[i-1][j-1]*tmp*(i-j+1);
			wh[i][j] %= M;
			if (j<2) continue;
			wh[i][j] += 
wh[i-1][j-2]*(tmp/2)*(i-j+2)*(tmp-1)*(i-j+1);
			wh[i][j] %= M;
		}
		for (int j=0;j<=n;j++) {
			wh[i+1][j] = wh[i][j];
		}
	}
	ll res = 0;
	for (int i=0;i<=n;i++) {
		if (k-i > n) {
			i = k-n;
			continue;
		}
		if (k-i < 0) break;
		res += bl[n][i]*wh[n][k-i];
		res %= M;
	}
	cout << res << "\n";
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED