Submission #391967

#	Time	Username	Problem	Language	Result	Execution time	Memory
391967		PixelCat	Tents (JOI18_tents)	C++14	100 / 100	171 ms	71108 KiB

tents

/*                                                       
  /^--^\                                                 
  \____/                                                 
 /      \ _____  _ __  __ ____  _     ____   ____  _____ 
|        || ()_)| |\ \/ /| ===|| |__ / (__` / () \|_   _|
 \__  __/ |_|   |_|/_/\_\|____||____|\____)/__/\__\ |_|  
|^|^\ \^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|^|
| | |\ \| | | | | | | | | | | | | | | | | | | | | | | | |
#####/ /#################################################
| | |\/ | | | | | | | | | | | | | | | | | | | | | | | | |
|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|*/
//#pragma GCC optimize("O4,unroll-loops,no-stack-protector")
#include <bits/stdc++.h>
#define int ll //__int128
#define double long double
using namespace std;
using ll=long long;
using ull=unsigned long long;
using pii=pair<int,int>;

#define For(i,a,b)    for(int i=a;i<=b;i++)
#define Fors(i,a,b,s) for(int i=a;i<=b;i+=s)
#define Forr(i,a,b)   for(int i=a;i>=b;i--)
#define F first
#define S second
#define L(id) (id*2+1)
#define R(id) (id*2+2)
#define LO(x) (x&(-x))

#define eb emplace_back
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define mkp make_pair

#define MOD (int)(1000000007)
#define INF (int)(1e12)
#define EPS (1e-7)

#ifdef NYAOWO
#define debug(...) do{\
	cerr << __LINE__ <<\
	" : ("#__VA_ARGS__ << ") = ";\
	_OUT(__VA_ARGS__);\
	cerr << flush;\
}while(0)
template<typename T> void _OUT(T x) { cerr << x << "\n"; }
template<typename T,typename...I>
void _OUT(T x,I ...tail) { cerr << x << ", "; _OUT(tail...); }
#else
#define debug(...)
#endif
inline void NYA(){ ios::sync_with_stdio(false); cin.tie(0); }
inline void USACO(const string &s){
	freopen((s+".in").c_str(),"r",stdin);
	freopen((s+".out").c_str(),"w",stdout);
}

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
//int gcd(int a,int b) { return b==0?a:gcd(b,a%b); }
inline int gcd(int a,int b) { return __gcd(a,b); }
inline int lcm(int a,int b) { return a/gcd(a,b)*b; }
__int128 fpow(__int128 b,__int128 p,const __int128 &mod){
	__int128 ans=1;
	while(p){
		if(p&1) ans=ans*b%mod;
		p/=2; b=b*b%mod;
	}
	return ans;
}
int fpow(int b,int p) { return fpow(b,p,MOD); }
template<typename T> inline void chmin(T &_a,const T &_b) { if(_b<_a) _a=_b; }
template<typename T> inline void chmax(T &_a,const T &_b) { if(_b>_a) _a=_b; }

int dp[3010][3010];
int fac[3010];
int inv[3010];
int C(int n,int m){
	return fac[n]*inv[m]%MOD*inv[n-m]%MOD;
}

int32_t main(){
	NYA();
	//nachoneko so cute >/////<
	fac[0]=inv[0]=1;
	For(i,1,3000){
		fac[i]=fac[i-1]*i%MOD;
		inv[i]=fpow(fac[i],MOD-2);
	}
	int n,m; cin>>n>>m;
	dp[0][0]=1;
	int ans=0;
	For(i,1,n) For(j,1,m){
		dp[i][j]=dp[i-1][j-1]*4*j;
		if(i>=2) dp[i][j]+=dp[i-2][j-1]*(i-1)*j;
		if(j>=2) dp[i][j]+=dp[i-1][j-2]*j*(j-1)/2;
		dp[i][j]%=MOD;
		ans=(ans+dp[i][j]*C(n,i)%MOD*C(m,j))%MOD;
		debug(i,j,dp[i][j]);
	}
	cout<<ans<<"\n";
	return 0;
}

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