Submission #1127660

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127660		VinhLuu	Tents (JOI18_tents)	C++20	100 / 100	176 ms	70804 KiB

tents

#include <bits/stdc++.h>
#define ll long long
#define all(lpv) lpv.begin(), lpv.end()
#define pot(x, y) lower_bound(x.begin(), x.end(), y) - x.begin() + 1
using namespace std;

#define lpv

#ifndef lpv
#include "AC.h"
#endif // lpv

#define int long long

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


int lt(int u,int v) {
  if(!v) return 1;
  int x = u, kq = 1;
  while(v) {
    if(v & 1) kq = kq * x % mod;
    x = x * x % mod;
    v /= 2;
  }
  return kq;
}

void get(int &x,int y) {
  x = (x + y) % mod;
}

int f[N][N], g[N][N], ft[N], inv[N];

int C(int u,int v) {
  if(!u || u == v) return 1;
  return ft[v] * inv[v - u] % mod * inv[u] % mod;
}

#ifdef lpv
signed main() {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  #define task "v"
  if(fopen(task ".inp","r")) {
    freopen(task ".inp","r",stdin);
    freopen(task ".out","w",stdout);
  }

  int n, m; cin >> n >> m;

  for(int i = 0; i <= n; i ++) {
    for(int j = 0; j <= m; j ++) {
      if(!i || !j) {f[i][j] = 1; continue;}
      get(f[i][j], f[i - 1][j - 1] * 4 % mod * j % mod);
      get(f[i][j], f[i - 1][j]);
      if(i >= 2) get(f[i][j], f[i - 2][j - 1] * (i - 1) % mod * j % mod);
      if(j >= 2) get(f[i][j], f[i - 1][j - 2] * ((j * (j - 1) / 2) % mod) % mod);
    }
  }

  cout << (f[n][m] - 1 + mod) % mod;

}
#endif // lpv

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     freopen(task ".inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:47:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     freopen(task ".out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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