#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=4e5+5;
const ll K=350;
const ld pi=3.14159265359;
const ll INF=(1LL<<40);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()
ll n,m,fac[N],rfac[N];
ll C(ll a,ll b){
return fac[a]*rfac[b]%MOD*rfac[a-b]%MOD;
}
ll po(ll base,ll ti){
ll res=1;
for(;ti;ti>>=1,base=base*base%MOD){
if(ti&1)res=res*base%MOD;
}
return res;
}
ll cal(ll k){
ll tmp=0;
for(int i=0,o=1;i<k;i++,o=-o)tmp=(tmp+1LL*o*C(n,i)*po(k-i,n))%MOD;
return (tmp+MOD)%MOD;
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
fac[0]=rfac[0]=1;
REP1(i,N-1)fac[i]=i*fac[i-1]%MOD,rfac[i]=rfac[i-1]*po(i,MOD-2)%MOD;
ll ans=cal(m)-cal(m-1);
cout<<(ans%MOD+MOD)%MOD<<"\n";
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
64 ms |
6648 KB |
Output is correct |
2 |
Correct |
66 ms |
6648 KB |
Output is correct |
3 |
Correct |
64 ms |
6524 KB |
Output is correct |
4 |
Correct |
64 ms |
6520 KB |
Output is correct |
5 |
Correct |
64 ms |
6652 KB |
Output is correct |
6 |
Correct |
64 ms |
6652 KB |
Output is correct |
7 |
Correct |
64 ms |
6520 KB |
Output is correct |
8 |
Correct |
64 ms |
6680 KB |
Output is correct |
9 |
Correct |
64 ms |
6648 KB |
Output is correct |
10 |
Correct |
64 ms |
6648 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
64 ms |
6648 KB |
Output is correct |
2 |
Correct |
66 ms |
6648 KB |
Output is correct |
3 |
Correct |
64 ms |
6524 KB |
Output is correct |
4 |
Correct |
64 ms |
6520 KB |
Output is correct |
5 |
Correct |
64 ms |
6652 KB |
Output is correct |
6 |
Correct |
64 ms |
6652 KB |
Output is correct |
7 |
Correct |
64 ms |
6520 KB |
Output is correct |
8 |
Correct |
64 ms |
6680 KB |
Output is correct |
9 |
Correct |
64 ms |
6648 KB |
Output is correct |
10 |
Correct |
64 ms |
6648 KB |
Output is correct |
11 |
Correct |
64 ms |
6648 KB |
Output is correct |
12 |
Correct |
65 ms |
6576 KB |
Output is correct |
13 |
Correct |
66 ms |
6648 KB |
Output is correct |
14 |
Correct |
65 ms |
6520 KB |
Output is correct |
15 |
Correct |
64 ms |
6648 KB |
Output is correct |
16 |
Correct |
65 ms |
6648 KB |
Output is correct |
17 |
Correct |
64 ms |
6648 KB |
Output is correct |
18 |
Correct |
64 ms |
6520 KB |
Output is correct |
19 |
Correct |
64 ms |
6520 KB |
Output is correct |
20 |
Correct |
65 ms |
6648 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
64 ms |
6648 KB |
Output is correct |
2 |
Correct |
66 ms |
6648 KB |
Output is correct |
3 |
Correct |
64 ms |
6524 KB |
Output is correct |
4 |
Correct |
64 ms |
6520 KB |
Output is correct |
5 |
Correct |
64 ms |
6652 KB |
Output is correct |
6 |
Correct |
64 ms |
6652 KB |
Output is correct |
7 |
Correct |
64 ms |
6520 KB |
Output is correct |
8 |
Correct |
64 ms |
6680 KB |
Output is correct |
9 |
Correct |
64 ms |
6648 KB |
Output is correct |
10 |
Correct |
64 ms |
6648 KB |
Output is correct |
11 |
Correct |
64 ms |
6648 KB |
Output is correct |
12 |
Correct |
65 ms |
6576 KB |
Output is correct |
13 |
Correct |
66 ms |
6648 KB |
Output is correct |
14 |
Correct |
65 ms |
6520 KB |
Output is correct |
15 |
Correct |
64 ms |
6648 KB |
Output is correct |
16 |
Correct |
65 ms |
6648 KB |
Output is correct |
17 |
Correct |
64 ms |
6648 KB |
Output is correct |
18 |
Correct |
64 ms |
6520 KB |
Output is correct |
19 |
Correct |
64 ms |
6520 KB |
Output is correct |
20 |
Correct |
65 ms |
6648 KB |
Output is correct |
21 |
Correct |
65 ms |
6620 KB |
Output is correct |
22 |
Correct |
65 ms |
6524 KB |
Output is correct |
23 |
Correct |
64 ms |
6520 KB |
Output is correct |
24 |
Correct |
64 ms |
6648 KB |
Output is correct |
25 |
Correct |
64 ms |
6520 KB |
Output is correct |
26 |
Correct |
65 ms |
6520 KB |
Output is correct |
27 |
Correct |
64 ms |
6520 KB |
Output is correct |
28 |
Correct |
66 ms |
6524 KB |
Output is correct |
29 |
Correct |
65 ms |
6648 KB |
Output is correct |
30 |
Correct |
66 ms |
6648 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
64 ms |
6648 KB |
Output is correct |
2 |
Correct |
66 ms |
6648 KB |
Output is correct |
3 |
Correct |
64 ms |
6524 KB |
Output is correct |
4 |
Correct |
64 ms |
6520 KB |
Output is correct |
5 |
Correct |
64 ms |
6652 KB |
Output is correct |
6 |
Correct |
64 ms |
6652 KB |
Output is correct |
7 |
Correct |
64 ms |
6520 KB |
Output is correct |
8 |
Correct |
64 ms |
6680 KB |
Output is correct |
9 |
Correct |
64 ms |
6648 KB |
Output is correct |
10 |
Correct |
64 ms |
6648 KB |
Output is correct |
11 |
Correct |
64 ms |
6648 KB |
Output is correct |
12 |
Correct |
65 ms |
6576 KB |
Output is correct |
13 |
Correct |
66 ms |
6648 KB |
Output is correct |
14 |
Correct |
65 ms |
6520 KB |
Output is correct |
15 |
Correct |
64 ms |
6648 KB |
Output is correct |
16 |
Correct |
65 ms |
6648 KB |
Output is correct |
17 |
Correct |
64 ms |
6648 KB |
Output is correct |
18 |
Correct |
64 ms |
6520 KB |
Output is correct |
19 |
Correct |
64 ms |
6520 KB |
Output is correct |
20 |
Correct |
65 ms |
6648 KB |
Output is correct |
21 |
Correct |
65 ms |
6620 KB |
Output is correct |
22 |
Correct |
65 ms |
6524 KB |
Output is correct |
23 |
Correct |
64 ms |
6520 KB |
Output is correct |
24 |
Correct |
64 ms |
6648 KB |
Output is correct |
25 |
Correct |
64 ms |
6520 KB |
Output is correct |
26 |
Correct |
65 ms |
6520 KB |
Output is correct |
27 |
Correct |
64 ms |
6520 KB |
Output is correct |
28 |
Correct |
66 ms |
6524 KB |
Output is correct |
29 |
Correct |
65 ms |
6648 KB |
Output is correct |
30 |
Correct |
66 ms |
6648 KB |
Output is correct |
31 |
Correct |
64 ms |
6520 KB |
Output is correct |
32 |
Correct |
64 ms |
6520 KB |
Output is correct |
33 |
Correct |
65 ms |
6520 KB |
Output is correct |
34 |
Correct |
67 ms |
6604 KB |
Output is correct |
35 |
Correct |
78 ms |
6520 KB |
Output is correct |
36 |
Correct |
80 ms |
6520 KB |
Output is correct |
37 |
Correct |
80 ms |
6648 KB |
Output is correct |
38 |
Correct |
66 ms |
6520 KB |
Output is correct |
39 |
Correct |
71 ms |
6648 KB |
Output is correct |
40 |
Correct |
72 ms |
6608 KB |
Output is correct |