#include<bits/stdc++.h>
using namespace std;
const long long maxn=100000+10;
long long mod=1e9+7;
long long fact[maxn],revfact[maxn];
long long mypow(long long m,long long y){
if(y==0){
return 1;
}
long long p=mypow(m,(y>>1));
p*=p;
p%=mod;
if(y&1){
p*=m;
p%=mod;
}
return p;
}
void aval(){
fact[0]=1;
for(long long i=1;i<maxn;i++){
fact[i]=1ll*fact[i-1]*i%mod;
}
revfact[maxn-1]=mypow(fact[maxn-1],mod-2);
for(long long i=maxn-2;i>=0;i--){
revfact[i]=1ll*revfact[i+1]*(i+1)%mod;
}
}
long long c(long long i,long long j){
if(i<0||j<0||i<j){
return 0;
}
return 1ll*fact[i]*revfact[j]%mod*revfact[i-j]%mod;
}
int main(){
aval();
long long n,k;
cin>>n>>k;
long long res=0;
for(long long i=k;i>=1;i--){
long long fake=mypow(i,n)*c(n+1,k-i)%mod;
if(i&1){
res-=fake;
}
else{
res+=fake;
}
//cout<<i<<" "<<fake<<" "<<mypow(i,n)<<" "<<c(n+1,k-i)<<endl;
}
//cout<<res<<endl;
//res+=1000000*mod;
//res%=mod;
res=abs(res);
res%=mod;
cout<<res<<"\n";
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 2 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 3 |
Correct |
3 ms |
1964 KB |
Output is correct |
| 4 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 5 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 6 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 7 |
Correct |
3 ms |
1792 KB |
Output is correct |
| 8 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 9 |
Correct |
3 ms |
2000 KB |
Output is correct |
| 10 |
Correct |
3 ms |
1884 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 2 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 3 |
Correct |
3 ms |
1964 KB |
Output is correct |
| 4 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 5 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 6 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 7 |
Correct |
3 ms |
1792 KB |
Output is correct |
| 8 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 9 |
Correct |
3 ms |
2000 KB |
Output is correct |
| 10 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 11 |
Correct |
3 ms |
1880 KB |
Output is correct |
| 12 |
Correct |
3 ms |
1904 KB |
Output is correct |
| 13 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 14 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 15 |
Incorrect |
3 ms |
1884 KB |
Output isn't correct |
| 16 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 2 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 3 |
Correct |
3 ms |
1964 KB |
Output is correct |
| 4 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 5 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 6 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 7 |
Correct |
3 ms |
1792 KB |
Output is correct |
| 8 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 9 |
Correct |
3 ms |
2000 KB |
Output is correct |
| 10 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 11 |
Correct |
3 ms |
1880 KB |
Output is correct |
| 12 |
Correct |
3 ms |
1904 KB |
Output is correct |
| 13 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 14 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 15 |
Incorrect |
3 ms |
1884 KB |
Output isn't correct |
| 16 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 2 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 3 |
Correct |
3 ms |
1964 KB |
Output is correct |
| 4 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 5 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 6 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 7 |
Correct |
3 ms |
1792 KB |
Output is correct |
| 8 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 9 |
Correct |
3 ms |
2000 KB |
Output is correct |
| 10 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 11 |
Correct |
3 ms |
1880 KB |
Output is correct |
| 12 |
Correct |
3 ms |
1904 KB |
Output is correct |
| 13 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 14 |
Correct |
3 ms |
1884 KB |
Output is correct |
| 15 |
Incorrect |
3 ms |
1884 KB |
Output isn't correct |
| 16 |
Halted |
0 ms |
0 KB |
- |
