Count Subarrays with Sum Divisible by K

Given an array ARR and an integer K, your task is to count all subarrays whose sum is divisible by the given integer K.

Input:

The first line of input contains an integer T representing the number of test cases.
The next 2*T lines represent the T test cases.

For each test case:
- The first line contains two space-separated integers: N (number of elements in the array) and K.
- The second line contains N space-separated integers representing the elements of the array.

Output:

For each test case, output a single integer, the count of all subarrays whose sum is divisible by K.

Example:

Input:

ARR = [5, 0, 2, 3, 1], K = 5

Output:

6

Explanation:

There are 6 subarrays with sums divisible by K.

Constraints:

• 1 ≤ T ≤ 50
• 1 ≤ K, N ≤ 104
• -109 ≤ ARR[i] ≤ 109
• Time limit: 1 second

Note:

If no subarray exists whose sum is divisible by K, return 0.