Submission #913949

#	Time	Username	Problem	Language	Result	Execution time	Memory
913949		penguin133	Tents (JOI18_tents)	C++17	100 / 100	197 ms	71568 KiB

tents

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

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

int memo[3005][3005];
const int mod = 1e9 + 7;

int dp(int x, int y){
	if(x <= 0 || y <= 0)return 1;
	if(memo[x][y] != -1)return memo[x][y];
	return memo[x][y] = (y * (y - 1) / 2 % mod * dp(x - 1, y - 2) % mod + (x - 1) * y  % mod * dp(x - 2, y - 1) % mod + 4 * y * dp(x - 1, y - 1) % mod + dp(x - 1, y) % mod)% mod;
}

void solve(){
	int n, m; cin >> n >> m;
	memset(memo, -1, sizeof(memo));
	cout << (dp(n, m) - 1 + mod) % mod << '\n';
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

tents.cpp:29:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   29 | main(){
      | ^~~~

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