#include <bits/stdc++.h>
#define int long long
const int mod=1e9+7LL;
using namespace std;
int n,k,fact[100005],inv[100005],invfact[100005],ans;
int fp(int x,int p){
if (!p) return 1LL;
int t=fp(x,p/2);
t=(t*t)%mod;
if (p&1LL) t*=x;
return t%mod;
}
int ncr(int x,int p){
return (fact[x]*invfact[p]%mod*invfact[x-p])%mod;
}
signed main(){
cin>>n>>k;
fact[0]=1LL;
k=n-k;
for (int i=1;i<=n+1;i++) fact[i]=(fact[i-1]*i)%mod;
inv[1]=invfact[0]=invfact[1]=1LL;
for (int i=2;i<=n+1;i++){
inv[i]=mod-mod/i*inv[mod%i]%mod;
invfact[i]=(invfact[i-1]*inv[i])%mod;
}
for (int i=0;i<=k;i++){
int cal=ncr(n+1,i)*fp(k+1LL-i,n)%mod;
if (i&1LL) ans+=(mod-cal);
else ans+=cal;
ans%=mod;
}
cout<<ans%mod<<"\n";
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
308 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Correct |
1 ms |
212 KB |
Output is correct |
| 5 |
Correct |
1 ms |
212 KB |
Output is correct |
| 6 |
Correct |
1 ms |
212 KB |
Output is correct |
| 7 |
Correct |
0 ms |
212 KB |
Output is correct |
| 8 |
Correct |
1 ms |
304 KB |
Output is correct |
| 9 |
Correct |
1 ms |
288 KB |
Output is correct |
| 10 |
Correct |
1 ms |
308 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
308 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Correct |
1 ms |
212 KB |
Output is correct |
| 5 |
Correct |
1 ms |
212 KB |
Output is correct |
| 6 |
Correct |
1 ms |
212 KB |
Output is correct |
| 7 |
Correct |
0 ms |
212 KB |
Output is correct |
| 8 |
Correct |
1 ms |
304 KB |
Output is correct |
| 9 |
Correct |
1 ms |
288 KB |
Output is correct |
| 10 |
Correct |
1 ms |
308 KB |
Output is correct |
| 11 |
Correct |
1 ms |
212 KB |
Output is correct |
| 12 |
Correct |
0 ms |
212 KB |
Output is correct |
| 13 |
Correct |
1 ms |
212 KB |
Output is correct |
| 14 |
Correct |
1 ms |
212 KB |
Output is correct |
| 15 |
Correct |
1 ms |
212 KB |
Output is correct |
| 16 |
Correct |
0 ms |
212 KB |
Output is correct |
| 17 |
Correct |
0 ms |
212 KB |
Output is correct |
| 18 |
Correct |
0 ms |
212 KB |
Output is correct |
| 19 |
Correct |
1 ms |
212 KB |
Output is correct |
| 20 |
Correct |
0 ms |
212 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
308 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Correct |
1 ms |
212 KB |
Output is correct |
| 5 |
Correct |
1 ms |
212 KB |
Output is correct |
| 6 |
Correct |
1 ms |
212 KB |
Output is correct |
| 7 |
Correct |
0 ms |
212 KB |
Output is correct |
| 8 |
Correct |
1 ms |
304 KB |
Output is correct |
| 9 |
Correct |
1 ms |
288 KB |
Output is correct |
| 10 |
Correct |
1 ms |
308 KB |
Output is correct |
| 11 |
Correct |
1 ms |
212 KB |
Output is correct |
| 12 |
Correct |
0 ms |
212 KB |
Output is correct |
| 13 |
Correct |
1 ms |
212 KB |
Output is correct |
| 14 |
Correct |
1 ms |
212 KB |
Output is correct |
| 15 |
Correct |
1 ms |
212 KB |
Output is correct |
| 16 |
Correct |
0 ms |
212 KB |
Output is correct |
| 17 |
Correct |
0 ms |
212 KB |
Output is correct |
| 18 |
Correct |
0 ms |
212 KB |
Output is correct |
| 19 |
Correct |
1 ms |
212 KB |
Output is correct |
| 20 |
Correct |
0 ms |
212 KB |
Output is correct |
| 21 |
Correct |
1 ms |
308 KB |
Output is correct |
| 22 |
Correct |
1 ms |
340 KB |
Output is correct |
| 23 |
Correct |
1 ms |
308 KB |
Output is correct |
| 24 |
Correct |
1 ms |
340 KB |
Output is correct |
| 25 |
Correct |
1 ms |
380 KB |
Output is correct |
| 26 |
Correct |
1 ms |
340 KB |
Output is correct |
| 27 |
Correct |
1 ms |
340 KB |
Output is correct |
| 28 |
Correct |
1 ms |
212 KB |
Output is correct |
| 29 |
Correct |
0 ms |
308 KB |
Output is correct |
| 30 |
Correct |
1 ms |
340 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
308 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
212 KB |
Output is correct |
| 4 |
Correct |
1 ms |
212 KB |
Output is correct |
| 5 |
Correct |
1 ms |
212 KB |
Output is correct |
| 6 |
Correct |
1 ms |
212 KB |
Output is correct |
| 7 |
Correct |
0 ms |
212 KB |
Output is correct |
| 8 |
Correct |
1 ms |
304 KB |
Output is correct |
| 9 |
Correct |
1 ms |
288 KB |
Output is correct |
| 10 |
Correct |
1 ms |
308 KB |
Output is correct |
| 11 |
Correct |
1 ms |
212 KB |
Output is correct |
| 12 |
Correct |
0 ms |
212 KB |
Output is correct |
| 13 |
Correct |
1 ms |
212 KB |
Output is correct |
| 14 |
Correct |
1 ms |
212 KB |
Output is correct |
| 15 |
Correct |
1 ms |
212 KB |
Output is correct |
| 16 |
Correct |
0 ms |
212 KB |
Output is correct |
| 17 |
Correct |
0 ms |
212 KB |
Output is correct |
| 18 |
Correct |
0 ms |
212 KB |
Output is correct |
| 19 |
Correct |
1 ms |
212 KB |
Output is correct |
| 20 |
Correct |
0 ms |
212 KB |
Output is correct |
| 21 |
Correct |
1 ms |
308 KB |
Output is correct |
| 22 |
Correct |
1 ms |
340 KB |
Output is correct |
| 23 |
Correct |
1 ms |
308 KB |
Output is correct |
| 24 |
Correct |
1 ms |
340 KB |
Output is correct |
| 25 |
Correct |
1 ms |
380 KB |
Output is correct |
| 26 |
Correct |
1 ms |
340 KB |
Output is correct |
| 27 |
Correct |
1 ms |
340 KB |
Output is correct |
| 28 |
Correct |
1 ms |
212 KB |
Output is correct |
| 29 |
Correct |
0 ms |
308 KB |
Output is correct |
| 30 |
Correct |
1 ms |
340 KB |
Output is correct |
| 31 |
Correct |
16 ms |
2644 KB |
Output is correct |
| 32 |
Correct |
15 ms |
2648 KB |
Output is correct |
| 33 |
Correct |
15 ms |
2644 KB |
Output is correct |
| 34 |
Correct |
13 ms |
2612 KB |
Output is correct |
| 35 |
Correct |
5 ms |
2644 KB |
Output is correct |
| 36 |
Correct |
4 ms |
2644 KB |
Output is correct |
| 37 |
Correct |
4 ms |
2604 KB |
Output is correct |
| 38 |
Correct |
2 ms |
692 KB |
Output is correct |
| 39 |
Correct |
7 ms |
2004 KB |
Output is correct |
| 40 |
Correct |
11 ms |
2644 KB |
Output is correct |
