Submission #717012

#	Time	Username	Problem	Language	Result	Execution time	Memory
717012		AmirAli_H1	Tents (JOI18_tents)	C++17	100 / 100	108 ms	70880 KiB

tents

// In the name of Allah

#include <bits/stdc++.h>
using namespace std;

typedef long long int	ll;
typedef long double	ld;
typedef pair<int, int>	pii;
typedef pair<ll, ll>	pll;

#define all(x)		(x).begin(),(x).end()
#define len(x)		((ll) (x).size())
#define F		first
#define S		second
#define pb		push_back
#define sep             ' '
#define endl            '\n'
#define Mp		make_pair
#define debug(x)	cerr << #x << ": " <<  x << endl;
#define kill(x)		cout << x << '\n', exit(0);
#define set_dec(x)	cout << fixed << setprecision(x);
#define file_io(x,y)	freopen(x, "r", stdin); freopen(y, "w", stdout);

int n, m;
const int maxn = 3000 + 4;
const int mod = 1e9 + 7;
ll dp[maxn][maxn];

int main() {
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	
	cin >> n >> m;
	
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= m; j++) dp[i][j] = 1;
	}
	
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			dp[i][j] = dp[i - 1][j];
			if (j - 2 >= 0) dp[i][j] += (1ll * (j * (j - 1) / 2)) % mod * dp[i - 1][j - 2] % mod;
			if (i - 2 >= 0) dp[i][j] += (1ll * j * (i - 1)) % mod * dp[i - 2][j - 1] % mod;
			dp[i][j] += (4ll * j) % mod * dp[i - 1][j - 1] % mod;
			dp[i][j] %= mod;
		}
	}
	
	cout << (dp[n][m] - 1 + mod) % mod << endl;
	
	return 0;
}

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