Submission #610089

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
610089	2022-07-28 04:53:40	penguinhacker	Tents (JOI18_tents)	C++17	100 / 100	117 ms	70764 KiB

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#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ar array
const int mxN=3000, M=1e9+7;
int n, m;
ll dp[mxN+1][mxN+1];
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  for (int i=0; i<=max(n, m); ++i)
    dp[0][i]=dp[i][0]=1;
  for (int i=1; i<=n; ++i)
    for (int j=1; j<=m; ++j) {
      // two tents on row 1
      dp[i][j]=dp[i-1][j];
      if (j>=2)
        dp[i][j]=(dp[i][j]+dp[i-1][j-2]*j*(j-1)/2)%M;
      dp[i][j]=(dp[i][j]+dp[i-1][j-1]*4*j)%M;
      if (i>=2)
        dp[i][j]=(dp[i][j]+dp[i-2][j-1]*j*(i-1))%M;
    }
  cout << (dp[n][m]-1+M)%M;
  return 0;
}
 
 
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• Subtask 1: 48 / 48
• Subtask 2: 52 / 52