Submission #1158042

#	Time	Username	Problem	Language	Result	Execution time	Memory
1158042		nguyn	Tents (JOI18_tents)	C++20	100 / 100	104 ms	70992 KiB

tents

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

#define int long long
#define ll long long 
#define F first
#define S second
#define pb push_back 
#define pii pair<int,int>

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

int n, m;
int f[N][N]; 

void add(int &x, int y) {
	if (y < 0) x += mod; 
	x += y; 
	if (x >= mod) x -= mod; 
}

signed main(){
    ios_base::sync_with_stdio(false) ; 
    cin.tie(0) ; cout.tie(0) ; 
    if (fopen("INP.INP" ,"r")) {
        freopen("INP.INP" ,"r" , stdin) ;
        freopen("OUT.OUT" , "w" , stdout) ;
    }
    cin >> n >> m;	
    for (int i = 0; i <= max(m, n); i++) {
    	f[i][0] = f[0][i] = 1; 
    }
    for (int i = 1; i <= n; i++) {
    	for (int j = 1; j <= m; j++) {
    		add(f[i][j], (f[i - 1][j - 1] * 4 * j + f[i - 1][j]) % mod);
    		if (i > 1) add(f[i][j], f[i - 2][j - 1] * j % mod * (i - 1) % mod);
    		if (j > 1) add(f[i][j], f[i - 1][j - 2] * (j * (j - 1) / 2 % mod) % mod); 
    	}
    }
    int res = f[n][m];
    add(res, -1);
    cout << res; 
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen("INP.INP" ,"r" , stdin) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:28:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen("OUT.OUT" , "w" , stdout) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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