Submission #472798

#	Time	Username	Problem	Language	Result	Execution time	Memory
472798		prvocislo	Tents (JOI18_tents)	C++17	100 / 100	268 ms	63312 KiB

tents

#include <iostream>
typedef long long ll;
using namespace std;

const int mod = 1e9 + 7, maxn = 3005;
int add(const int& a, const int& b) { return (a + b) % mod; }
int mul(const int& a, const int& b) { return (a * 1ll * b) % (ll)mod; }
void upd(int& a, const int& b) { a = (a + b) % mod; }
int dp[maxn][maxn], p[maxn][maxn];
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	p[0][0] = 1;
	for (int i = 1; i < maxn; i++)
	{
		p[i][0] = p[i][i] = 1;
		for (int j = 1; j < i; j++) p[i][j] = add(p[i - 1][j - 1], p[i - 1][j]);
	}
	dp[0][0] = 1;
	int h, w;
	cin >> h >> w;
	for (int i = 0; i < h; i++) for (int j = 0; j < w; j++)
	{
		upd(dp[i + 1][j + 1], mul(dp[i][j], mul(4, j + 1)));
		if (i + 2 <= h) upd(dp[i + 2][j + 1], mul(dp[i][j], mul(i + 1, j + 1)));
		if (j + 2 <= w) upd(dp[i + 1][j + 2], mul(dp[i][j], (j + 1) * (j + 2)/ 2));
	}
	int ans = 0;
	for (int i = 1; i <= h; i++) for (int j = 1; j <= w; j++)
	{
		int a = mul(dp[i][j], mul(p[h][i], p[w][j]));
		upd(ans, a);
	}
	cout << ans << "\n";
	return 0;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52