#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int readint(){
int x=0,f=1; char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
const int cys=1000000007;
int n,k;
ll fac[100005],inv[100005];
int mod(int x){return x>=cys?x-cys:x;}
ll qpow(ll x,ll p){
ll ret=1;
for(;p;p>>=1,x=x*x%cys) if(p&1) ret=ret*x%cys;
return ret;
}
int main(){
n=readint(); k=n-readint()+1;
fac[0]=inv[0]=1;
for(int i=1;i<=n+1;i++) fac[i]=fac[i-1]*i%cys,inv[i]=qpow(fac[i],cys-2);
ll ans=0;
for(int i=0;i<=k;i++) ans=mod(ans+((i&1)?cys-1:1)*qpow(k-i,n)%cys*fac[n+1]%cys*inv[i]%cys*inv[n-i+1]%cys);
printf("%lld\n",ans);
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
512 KB |
Output is correct |
| 2 |
Correct |
2 ms |
384 KB |
Output is correct |
| 3 |
Correct |
3 ms |
256 KB |
Output is correct |
| 4 |
Correct |
2 ms |
384 KB |
Output is correct |
| 5 |
Correct |
3 ms |
384 KB |
Output is correct |
| 6 |
Correct |
2 ms |
256 KB |
Output is correct |
| 7 |
Correct |
2 ms |
384 KB |
Output is correct |
| 8 |
Correct |
2 ms |
372 KB |
Output is correct |
| 9 |
Correct |
2 ms |
428 KB |
Output is correct |
| 10 |
Correct |
3 ms |
384 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
512 KB |
Output is correct |
| 2 |
Correct |
2 ms |
384 KB |
Output is correct |
| 3 |
Correct |
3 ms |
256 KB |
Output is correct |
| 4 |
Correct |
2 ms |
384 KB |
Output is correct |
| 5 |
Correct |
3 ms |
384 KB |
Output is correct |
| 6 |
Correct |
2 ms |
256 KB |
Output is correct |
| 7 |
Correct |
2 ms |
384 KB |
Output is correct |
| 8 |
Correct |
2 ms |
372 KB |
Output is correct |
| 9 |
Correct |
2 ms |
428 KB |
Output is correct |
| 10 |
Correct |
3 ms |
384 KB |
Output is correct |
| 11 |
Correct |
3 ms |
384 KB |
Output is correct |
| 12 |
Correct |
3 ms |
384 KB |
Output is correct |
| 13 |
Correct |
3 ms |
256 KB |
Output is correct |
| 14 |
Correct |
3 ms |
384 KB |
Output is correct |
| 15 |
Correct |
2 ms |
384 KB |
Output is correct |
| 16 |
Correct |
3 ms |
384 KB |
Output is correct |
| 17 |
Correct |
3 ms |
384 KB |
Output is correct |
| 18 |
Correct |
2 ms |
384 KB |
Output is correct |
| 19 |
Correct |
3 ms |
384 KB |
Output is correct |
| 20 |
Correct |
4 ms |
384 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
512 KB |
Output is correct |
| 2 |
Correct |
2 ms |
384 KB |
Output is correct |
| 3 |
Correct |
3 ms |
256 KB |
Output is correct |
| 4 |
Correct |
2 ms |
384 KB |
Output is correct |
| 5 |
Correct |
3 ms |
384 KB |
Output is correct |
| 6 |
Correct |
2 ms |
256 KB |
Output is correct |
| 7 |
Correct |
2 ms |
384 KB |
Output is correct |
| 8 |
Correct |
2 ms |
372 KB |
Output is correct |
| 9 |
Correct |
2 ms |
428 KB |
Output is correct |
| 10 |
Correct |
3 ms |
384 KB |
Output is correct |
| 11 |
Correct |
3 ms |
384 KB |
Output is correct |
| 12 |
Correct |
3 ms |
384 KB |
Output is correct |
| 13 |
Correct |
3 ms |
256 KB |
Output is correct |
| 14 |
Correct |
3 ms |
384 KB |
Output is correct |
| 15 |
Correct |
2 ms |
384 KB |
Output is correct |
| 16 |
Correct |
3 ms |
384 KB |
Output is correct |
| 17 |
Correct |
3 ms |
384 KB |
Output is correct |
| 18 |
Correct |
2 ms |
384 KB |
Output is correct |
| 19 |
Correct |
3 ms |
384 KB |
Output is correct |
| 20 |
Correct |
4 ms |
384 KB |
Output is correct |
| 21 |
Correct |
4 ms |
384 KB |
Output is correct |
| 22 |
Correct |
5 ms |
384 KB |
Output is correct |
| 23 |
Correct |
3 ms |
384 KB |
Output is correct |
| 24 |
Correct |
2 ms |
384 KB |
Output is correct |
| 25 |
Correct |
2 ms |
384 KB |
Output is correct |
| 26 |
Correct |
2 ms |
384 KB |
Output is correct |
| 27 |
Correct |
3 ms |
384 KB |
Output is correct |
| 28 |
Correct |
4 ms |
384 KB |
Output is correct |
| 29 |
Correct |
3 ms |
384 KB |
Output is correct |
| 30 |
Correct |
3 ms |
384 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
512 KB |
Output is correct |
| 2 |
Correct |
2 ms |
384 KB |
Output is correct |
| 3 |
Correct |
3 ms |
256 KB |
Output is correct |
| 4 |
Correct |
2 ms |
384 KB |
Output is correct |
| 5 |
Correct |
3 ms |
384 KB |
Output is correct |
| 6 |
Correct |
2 ms |
256 KB |
Output is correct |
| 7 |
Correct |
2 ms |
384 KB |
Output is correct |
| 8 |
Correct |
2 ms |
372 KB |
Output is correct |
| 9 |
Correct |
2 ms |
428 KB |
Output is correct |
| 10 |
Correct |
3 ms |
384 KB |
Output is correct |
| 11 |
Correct |
3 ms |
384 KB |
Output is correct |
| 12 |
Correct |
3 ms |
384 KB |
Output is correct |
| 13 |
Correct |
3 ms |
256 KB |
Output is correct |
| 14 |
Correct |
3 ms |
384 KB |
Output is correct |
| 15 |
Correct |
2 ms |
384 KB |
Output is correct |
| 16 |
Correct |
3 ms |
384 KB |
Output is correct |
| 17 |
Correct |
3 ms |
384 KB |
Output is correct |
| 18 |
Correct |
2 ms |
384 KB |
Output is correct |
| 19 |
Correct |
3 ms |
384 KB |
Output is correct |
| 20 |
Correct |
4 ms |
384 KB |
Output is correct |
| 21 |
Correct |
4 ms |
384 KB |
Output is correct |
| 22 |
Correct |
5 ms |
384 KB |
Output is correct |
| 23 |
Correct |
3 ms |
384 KB |
Output is correct |
| 24 |
Correct |
2 ms |
384 KB |
Output is correct |
| 25 |
Correct |
2 ms |
384 KB |
Output is correct |
| 26 |
Correct |
2 ms |
384 KB |
Output is correct |
| 27 |
Correct |
3 ms |
384 KB |
Output is correct |
| 28 |
Correct |
4 ms |
384 KB |
Output is correct |
| 29 |
Correct |
3 ms |
384 KB |
Output is correct |
| 30 |
Correct |
3 ms |
384 KB |
Output is correct |
| 31 |
Correct |
28 ms |
1920 KB |
Output is correct |
| 32 |
Correct |
28 ms |
1880 KB |
Output is correct |
| 33 |
Correct |
27 ms |
1920 KB |
Output is correct |
| 34 |
Correct |
25 ms |
1912 KB |
Output is correct |
| 35 |
Correct |
18 ms |
1920 KB |
Output is correct |
| 36 |
Correct |
19 ms |
1920 KB |
Output is correct |
| 37 |
Correct |
18 ms |
1920 KB |
Output is correct |
| 38 |
Correct |
6 ms |
564 KB |
Output is correct |
| 39 |
Correct |
17 ms |
1536 KB |
Output is correct |
| 40 |
Correct |
21 ms |
1904 KB |
Output is correct |
