Submission #168881

#	Time	Username	Problem	Language	Result	Execution time	Memory
168881		triplem5ds	Tents (JOI18_tents)	C++14	100 / 100	272 ms	36076 KiB

tents

#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")

#include "bits/stdc++.h"
using namespace std;

#define pb push_back
#define F first
#define S second
#define f(i,a,b)  for(int i = a; i < b; i++)
//#define endl '\n'

using ll = long long;
using db = long double;
using row = vector<int>;
using ii = pair<int, int>;

const int N = 1e5 + 5, M = 1e6 + 5, A = 6561, LG = 18, MOD = 1e9 + 7;
const int BLOCK = 1900;
const int BLOCKN = N / BLOCK + 1;
const long double EPS = 1e-7;
int dp[3005][3005];
int n, m;
int solve(int col, int emptyRows){
  if(col == 0)return 1;
  int &ret = dp[col][emptyRows];
  if(~ret)
    return ret;
  ///put nothing
  ret = solve(col-1,emptyRows);
  ///put two S and N have to be emptyRows
  if(emptyRows>=2)
    ret = (ret + solve(col-1,emptyRows-2) * 1ll * emptyRows * (emptyRows-1)/2) % MOD;
  ///put an S or an N or a W
  if(emptyRows)
    ret = (ret + solve(col-1,emptyRows-1) * 3ll * emptyRows)%MOD;
  ///put an E with no follow up
  if(emptyRows)
    ret = (ret + solve(col-1,emptyRows-1)*1ll*emptyRows)%MOD;
  ///put a E and W combo
  if(emptyRows&&col>=2)
    ret = (ret + solve(col-2,emptyRows-1)*1ll*emptyRows*(col-1))%MOD;
  return ret;
}
int main(){
#ifdef ONLINE_JUDGE
  ios_base::sync_with_stdio(0);
  cin.tie(0);
#endif // ONLINE_JUDGE

  cin>>n>>m;
  memset(dp,-1,sizeof dp);
  cout<<solve(m,n)-1<<'\n';

  return 0;
}

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