杭电 5363 求集合的非空子集中key的数量

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  , indicating the number of test cases. For each test case: 

The first line contains an integer  , 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

 

 

#include<cstdio>
__int64 f(__int64 a)
{
    __int64 b=2;
    __int64 t=1;
    while(a)
    {
        if(a % 2 != 0)
        {
            t=(t*b)%1000000007;
        }
        b=b*b%1000000007;
        a/=2;
    }
    return t;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        __int64 n;
        scanf("%I64d",&n);
        printf("%I64d\n",f(n-1)-1);
    }
    
}