【JZOJ4742】【NOIP2016提高A组模拟9.2】单峰

题目描述

输入

输出

样例输入

样例输出

数据范围

解法

代码

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define ll long long
#define sqr(x) ((x)*(x))
#define ln(x,y) int(log(x)/log(y))
using namespace std;
const char* fin="aP1.in";
const char* fout="aP1.out";
const int inf=0x7fffffff;
const int mo=1000000007;
ll n;
ll ans;
ll qpower(ll a,ll b){
ll c=1;
while (b){
if (b&1) c=(c*a)%mo;
a=(a*a)%mo;
b>>=1;
}
return c;
}
int main(){
scanf("%lld",&n);
ans=qpower(2,n-1);
printf("%lld",ans);
return 0;
}

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