#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;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
332 KB |
Output is correct |
| 2 |
Correct |
0 ms |
332 KB |
Output is correct |
| 3 |
Correct |
1 ms |
332 KB |
Output is correct |
| 4 |
Correct |
0 ms |
332 KB |
Output is correct |
| 5 |
Correct |
1 ms |
204 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
332 KB |
Output is correct |
| 2 |
Correct |
1 ms |
332 KB |
Output is correct |
| 3 |
Correct |
1 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
332 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
332 KB |
Output is correct |
| 2 |
Correct |
0 ms |
332 KB |
Output is correct |
| 3 |
Correct |
1 ms |
332 KB |
Output is correct |
| 4 |
Correct |
0 ms |
332 KB |
Output is correct |
| 5 |
Correct |
1 ms |
204 KB |
Output is correct |
| 6 |
Correct |
2 ms |
332 KB |
Output is correct |
| 7 |
Correct |
1 ms |
332 KB |
Output is correct |
| 8 |
Correct |
1 ms |
332 KB |
Output is correct |
| 9 |
Correct |
1 ms |
332 KB |
Output is correct |
| 10 |
Correct |
16 ms |
332 KB |
Output is correct |
| 11 |
Correct |
6 ms |
332 KB |
Output is correct |
| 12 |
Correct |
1 ms |
332 KB |
Output is correct |
| 13 |
Correct |
8 ms |
332 KB |
Output is correct |
| 14 |
Correct |
12 ms |
436 KB |
Output is correct |
| 15 |
Correct |
5 ms |
344 KB |
Output is correct |
| 16 |
Correct |
43 ms |
460 KB |
Output is correct |
| 17 |
Correct |
77 ms |
408 KB |
Output is correct |
| 18 |
Correct |
1 ms |
332 KB |
Output is correct |
