Key Set

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)

Total Submission(s): 722 Accepted Submission(s): 442

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

Source

2015 Multi-University Training Contest 6

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快速幂

#include <map>

#include <list>

#include <climits>

#include <cmath>

#include <queue>

#include <stack>

#include <string>

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>

using namespace std;

#define eps 1e-9

#define LL long long

#define PI acos(-1.0)

#define INF 0x3f3f3f3f

#define CRR fclose(stdin)

#define CWW fclose(stdout)

#define RR freopen("input.txt","r",stdin)

#define WW freopen("output.txt","w",stdout)

const int Max = 10010;

const int Mod = 1000000007;

LL pow_mod(LL n)

{

    LL res=1;

    LL a=2;

    while(n)

    {

        if(n&1)

        {

            res=(res*a)%Mod;

        }

        a=(a*a)%Mod;

        n>>=1;

    }

    return res;

}

int main()

{

    int T;

    scanf("%d",&T);

    LL n;

    while(T--)

    {

        scanf("%I64d",&n);

        printf("%I64d\n",pow_mod(n-1)-1);

    }

    return 0;

}

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