Submission #491182

#	Time	Username	Problem	Language	Result	Execution time	Memory
491182		inksamurai	Anagramistica (COCI21_anagramistica)	C++17	110 / 110	77 ms	460 KiB

anagramistica

#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(),a.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define crep(i,x,n) for(int i=x;i<n;i++)
#define drep(i,n) for(int i=n-1;i>=0;i--)
#define vec(...) vector<__VA_ARGS__>
#define _3cSpNGp ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
using pii=pair<int,int>;
using vi=vector<int>;

//snuke's mod int
template <ll mod>
struct modint{
  ll x; // typedef long long ll;
  modint(ll x=0):x((x%mod+mod)%mod){}
  modint operator-()const{ return modint(-x);}
  modint& operator+=(const modint a){ if((x+=a.x)>=mod) x-=mod; return *this; }
  modint& operator-=(const modint a){ if((x+=mod-a.x)>=mod) x-=mod; return *this; }
  modint& operator*=(const modint a){ (x*=a.x)%=mod; return *this; }
  modint operator+(const modint a)const{ modint res(*this); return res+=a; }
  modint operator-(const modint a)const{ modint res(*this); return res-=a; }
  modint operator*(const modint a)const{ modint res(*this); return res*=a; }
  modint pow(ll n) const {
    modint res=1,x(*this);
    while(n){
        if(n&1)res*=x;
        x*=x;
        n>>=1;
    }
    return res;
  }
  modint inv() const { return pow(mod-2); }
};
using mint=modint<1000000007>;

const int mxn=3000;
mint fact[mxn+10];
void prefact(){
fact[0]=fact[1]=1;
  crep(i,2,mxn){
    mint x=i;
    fact[i]=fact[i-1]*x;
  }
}

mint cnk(ll k,ll n){
  if(k>n) return 0;
  mint e=fact[k]*fact[n-k];
  return fact[n] * e.inv();
}

int main(){
_3cSpNGp;
prefact();
	int n,k;
	cin>>n>>k;
	vec(string) a(n);
	rep(i,n){
		cin>>a[i];
	}
	std::map<string,int> mp;
	rep(i,n){
		sort(a[i].begin(),a[i].end());
		mp[a[i]]++;
	}
	vi rbts;
	for(auto p : mp){
		rbts.pb(p.se);
	}
	n=sz(rbts);
	vec(mint) dp(k+1),nedp;
	dp[0]=1;
	rep(i,n){
		nedp=dp;
		int x=rbts[i];
		rep(j,k+1){
			if(dp[j].x==0) continue;
			for(int now=1;now<=x;now++){
				if(j+now*(now-1)/2>k) break;
				nedp[j+now*(now-1)/2]+=dp[j]*cnk(now,x);
			}
		}
		swap(dp,nedp);
	}
	// cout<<"\n";
	cout<<dp[k].x<<"\n";
//	
	return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 70 / 70