Submission #1033966

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033966		vjudge1	Tents (JOI18_tents)	C++14	100 / 100	93 ms	70844 KiB

tents

#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define name "aaaaaa"
using ll = long long;
using pll = pair<ll, ll>;
using ld = long double;

void file(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    if(fopen(name".inp", "r")) {
        freopen(name".inp", "r", stdin);
        freopen(name".out", "w", stdout);
    }
}

const int maxn = 3e3 + 5;
const ll mod = 1e9 + 7;

ll dp[maxn][maxn];

void solve (){
	int n, m;
	cin >> n >> m;
	for(int i = 0; i < maxn; i++){
		dp[0][i] = 1;
		dp[i][0] = 1;
	}
	for(ll i = 1; i <= n; i++){
		for(ll j = 1; j <= m; j++){
			dp[i][j] += dp[i - 1][j];
			dp[i][j] += dp[i - 1][j - 1] * 4 * j % mod;
			if(j >= 2) dp[i][j] += dp[i - 1][j - 2] * (j * (j - 1) / 2 % mod) % mod;
			if(i >= 2) dp[i][j] += j * (i - 1) % mod * dp[i - 2][j - 1] % mod;
			dp[i][j] %= mod;
		}
	}
	dp[n][m]--;
	if(dp[n][m] < 0) dp[n][m] += mod;
	cout << dp[n][m];
}

int main(){
    file();
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
}

Compilation message (stderr)

tents.cpp: In function 'void file()':
tents.cpp:12:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:13:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |         freopen(name".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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