Submission #49057

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
49057	2018-05-21 14:46:29	Namnamseo	Tents (JOI18_tents)	C++17	100 / 100	668 ms	63996 KiB

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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll dp[3010][3010];
const ll mod = 1'000'000'007;
ll f(ll w, ll h){
  if(!w || !h) return 1;
  if(w<0 || h<0) return 0;
  if(dp[w][h]) return dp[w][h];
  ll ret = 0;
  ret += f(w, h-1);
  (ret += w * 4 * f(w-1, h-1) % mod) %= mod;
  (ret += w*(w-1)/2 % mod * f(w-2, h-1) % mod) %= mod;
  (ret += w * (h-1) % mod * f(w-1, h-2) % mod) %= mod;
  return dp[w][h]=ret;
}
int main()
{
  int n, m; cin >> n >> m;
  cout << (f(n, m) + mod - 1) % mod << endl;
  return 0;
}
 
 
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• Subtask 1: 48 / 48
• Subtask 2: 52 / 52