hdu 5363Key Set

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5363

Problem Description

soda has a set S with n integers {1,2,…,n}. A set is called key set if the sum of integers in the set is an even number. He wants to know how many nonempty subsets of S are key set.

 

 

Input

There are multiple test cases. The first line of input contains an integer T (1≤T≤105), indicating the number of test cases. For each test case:

The first line contains an integer n (1≤n≤109), the number of integers in the set.

 

 

Output

For each test case, output the number of key sets modulo 1000000007.

 

 

Sample Input

4 1 2 3 4

 

 

Sample Output

0 1 3 7

 一看数据就是快速幂，一开始用int错了，索性全改为long long

#include <iostream>
#include <cmath>
using namespace std;

long long f(long long a)
{
    long long temp=2;
    long long ans=1;
    while (a)
    {
          if (a%2!=0)
          ans*=temp;
          
          ans=ans%1000000007;
          temp=temp*temp;
          temp=temp%1000000007;
          a/=2;
    }
    return ans;
}
int main()
{
     long long n,m;
     cin>>n;
     while (n--)
     {
           cin>>m;
           cout <<f(m-1)-1<<endl;
     }
     return 0;
}