Скачать или смотреть Codeforces Pleasant Pairs | Codeforces | Python Solution

#codeforces #PleasantPairs #AlbertLectures #CodingSolution

B. Pleasant Pairs

You are given an array a1,a2,…,an consisting of n distinct integers. Count the number of pairs of indices (i,j) such that i is less than j and ai*aj=i+j.

Input
The first line contains one integer t [1,10^4] — the number of test cases. Then t cases follow.

The first line of each test case contains one integer n [2,10^5] — the length of array a.

The second line of each test case contains n space separated integers a1,a2,…,an , ai = [1,2*n] — the array a. It is guaranteed that all elements are distinct.

It is guaranteed that the sum of n over all test cases does not exceed 2⋅105.

Output
For each test case, output the number of pairs of indices (i,j) such that i is less than j and ai*aj=i+j.