Submission #44366

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
44366	2018-04-01 05:30:45	Bruteforceman	Tents (JOI18_tents)	C++11	100 / 100	239 ms	36224 KiB

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#include <bits/stdc++.h>
using namespace std;
const int mod = 1000000007;
int mem[3003][3003];
long long dp(int H, int W) {
  if(H < 0) return 0;
  if(W < 0) return 0;
  if(H == 0 || W == 0) return 1;
  if(mem[H][W] != -1) return mem[H][W];
  long long ans = 0;
  ans += dp(H - 1, W);
  ans += dp(H - 1, W - 2) * ((W * (W - 1)) / 2); 
  ans += 4LL * dp(H - 1, W - 1) * W;
  ans += dp(H - 2, W - 1) * W * (H - 1);
  ans %= mod;
  return mem[H][W] = ans;
}
int main() {
  memset(mem, -1, sizeof mem);
  int H, W;
  cin >> H >> W;
  long long ans = dp(H, W) - 1;
  if(ans < 0) ans += mod;
  cout << ans << endl;
  return 0;
}
 
 
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• Subtask 1: 48 / 48
• Subtask 2: 52 / 52