Submission #711220

#	Time	Username	Problem	Language	Result	Execution time	Memory
711220		Radin_Zahedi2	Tents (JOI18_tents)	C++17	100 / 100	149 ms	35520 KiB

tents

#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define sz(x) (int)x.size()
#define endl '\n'
const int mod = 1e9 + 7;
const int inf = 2e9 + 5;
const ll linf = 9e18 + 5;


int n, m;
const int N = 3e3 + 5;
const int M = 3e3 + 5;
int dp[N][M];

int mull(int a, int b) {
	return (1ll * a * b) % mod;
}

int c2(int n) {
	return (1ll * n * (n - 1)) / 2;
}

void init() {
}

void input() {
	cin >> n >> m;
}

void solve() {
	for (int j = 0; j <= m; j++) {
		dp[0][j] = 1;
	}

	for (int i = 1; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			dp[i][j] = dp[i - 1][j];

			if (j >= 1) {
				dp[i][j] += mull(mull(j, 4), dp[i - 1][j - 1]);
				dp[i][j] %= mod;
			}

			if (i >= 2) {
				dp[i][j] += mull(mull(j, i - 1), dp[i - 2][j - 1]);
				dp[i][j] %= mod;
			}

			if (i >= 1 && j >= 2) {
				dp[i][j] += mull(c2(j), dp[i - 1][j - 2]);
				dp[i][j] %= mod;
			}
		}
	}

	cout << dp[n][m] - 1;
}

void output() {
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int number_of_testcases = 1;
	//cin >> number_of_testcases;
	while (number_of_testcases--) {
		init();

		input();

		solve();

		output();
	}

	return 0;
}

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