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问题 1864 --Inverse of sum

1864: Inverse of sum

时间限制: 6 Sec  内存限制: 128 MB
提交: 5  解决: 4
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题目描述

There are n nonnegative integers a1…n which are less than p. HazelFan wants to know how many pairs i,j(1≤i<j≤n) are there, satisfying 1/(ai+aj)≡1/ai+1/aj when we calculate module p, which means the inverse element of their sum equals the sum of their inverse elements. Notice that zero element has no inverse element.
 

输入描述

The first line contains a positive integer T(1≤T≤5), denoting the number of test cases.
For each test case:
The first line contains two positive integers n,p(1≤n≤10^5,2≤p≤10^18), and it is guaranteed that p is a prime number.
The second line contains n nonnegative integers a1...n(0≤ai<p).
 

输出描述

For each test case:
A single line contains a nonnegative integer, denoting the answer.
 

样例输入

2
5 7
1 2 3 4 5
6 7
1 2 3 4 5 6

样例输出

4
6

来源

 

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