Submission #1129896

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129896		aykhn	Tents (JOI18_tents)	C++20	100 / 100	90 ms	70904 KiB

tents

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int mod = 1e9 + 7;

signed main()
{
  int n, m;
  cin >> n >> m;
  int dp[n + 1][m + 1];
  for (int i = 0; i <= n; i++) for (int j = 0; j <= m; j++) dp[i][j] = !i || !j;
  for (int i = 1; i <= n; i++)
  {
    for (int j = 1; j <= m; j++)
    {
      dp[i][j] += dp[i - 1][j];
      dp[i][j] += dp[i - 1][j - 1] * j * 4;
      if (j > 1) dp[i][j] += dp[i - 1][j - 2] * j * (j - 1) / 2;
      if (i > 1) dp[i][j] += dp[i - 2][j - 1] * j * (i - 1);
      dp[i][j] %= mod;
    }
  }
  cout << (dp[n][m] + mod - 1) % mod << '\n';
}

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