牛客網 牛客小白月賽8 C-神祕鑰匙
阿新 • • 發佈:2019-02-02
玄學之門
題目:
分析:
數論題,沒什麼可以多說,直接證明:
證畢.
程式碼:
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<set>
#include<queue>
#include<vector>
#include<map>
#include<list>
#include<ctime>
#include<iomanip>
#include<string>
#include<bitset>
#include<deque>
#include<set>
#define XJQ 1000000007
#define LL long long
using namespace std;
inline LL read() {
LL d=0,f=1;char s=getchar ();
while(s<'0'||s>'9'){if(s=='-')f=-1;s=getchar();}
while(s>='0'&&s<='9'){d=d*10+s-'0';s=getchar();}
return d*f;
}
LL n=read();
LL king(LL w)
{
LL x=1,a=2;
while(w)
{
if(w&1) x=x*a%XJQ;
a=a*a%XJQ;
w>>=1;
}
return x;
}
int main()
{
printf("%lld",king(n-1)*n%XJQ);
return 0;
}