# |
Author |
Problem |
Lang |
Verdict |
Time |
Memory |
Sent |
Judged |
|
60909500 |
Practice:
Zory |
932E
- 28
|
C++17 (GCC 7-32)
|
Accepted
|
311 ms
|
196480 KB
|
2019-09-20 08:01:41 |
2019-09-20 08:01:41 |
|
#include<bits/stdc++.h>
using namespace std;
namespace mine
{
typedef long long ll;
#define pr pair<int,int>
#define FR first
#define SE second
#define MP make_pair
#define PB push_back
#define vc vector
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define bin(x) (1ll<<(x))
#define GG(x) if(x) puts("error")
ll qread()
{
ll ans=0,f=1;char c=getchar();
while(c<'0' or c>'9') {if(c=='-')f=-1;c=getchar();}
while('0'<=c and c<='9') ans=ans*10+c-'0',c=getchar();
return ans*f;
}
void write(ll num)
{
if(num<0) putchar('-'),num=-num;
if(num>=10) write(num/10);
putchar('0'+num%10);
}
void write1(ll num){write(num);putchar(' ');}
void write2(ll num){write(num);putchar('\n');}
template<typename T> void chmax(T &x,const T y) {x=(x>y?x:y);}
template<typename T> void chmin(T &x,const T y) {x=(x<y?x:y);}
ll gcd(ll x,ll y){return y?gcd(y,x%y):x;}
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
inline int mm(const int x){return x>=MOD?x-MOD:x;}
template<typename T> inline void add(T &x,const T y){x=mm(x+y);}
inline ll qpower(ll x,ll e)
{
ll ans=1;GG(e<0);
while(e){if(e&1)ans=ans*x%MOD;x=x*x%MOD;e>>=1;}return ans;
}
ll invm(ll x){return qpower(x,MOD-2);}
const int N=5e3+10;
ll s2[N][N];
void main()
{
s2[0][0]=1;for(int i=1;i<N;i++) for(int j=1;j<=i;j++) s2[i][j]=(s2[i-1][j]*j+s2[i-1][j-1])%MOD;
int n=qread(),k=qread();ll ans=0;
for(int j=0;j<=k;j++)
{
ll pp=1;for(int i=n;i>=n-j+1;i--) pp=pp*i%MOD;
if(n>=j) add(ans, s2[k][j]*pp%MOD*qpower(2,n-j)%MOD );
}write(ans);
}//(ans+MOD)%MOD
};
int main()
{
srand(time(0));
mine::main();
}
Click to see test details