HDU 6027 Easy Summation【简单相加||快速幂】

Easy Summation

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 965    Accepted Submission(s): 389

Problem Description

You are encountered with a traditional problem concerning the sums of powers.
Given two integers  n and  k. Let  f(i)=ik, please evaluate the sum  f(1)+f(2)+...+f(n). The problem is simple as it looks, apart from the value of  n in this question is quite large.
Can you figure the answer out? Since the answer may be too large, please output the answer modulo  109+7.

 

Input

The first line of the input contains an integer  T(1≤T≤20), denoting the number of test cases.
Each of the following  T lines contains two integers  n(1≤n≤10000) and  k(0≤k≤5).

 

Output

For each test case, print a single line containing an integer modulo  109+7.

 

Sample Input

3 2 5 4 2 4 1

 

Sample Output

33 30 10

 

Source

2017中国大学生程序设计竞赛 - 女生专场

注意：

fast_pow(ll p, ll n)中p可能爆int需写成long long

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