Given an array A[] and positive integer K, the task is to count total number of pairs in the array whose sum is divisible by K.
Example 1:
Input :
A[] = {2, 2, 1, 7, 5, 3}, K = 4
Output : 5
Explanation :
There are five pairs possible whose sum
is divisible by '4' i.e., (2, 2),
(1, 7), (7, 5), (1, 3) and (5, 3)
Example 2:
Input :
A[] = {5, 9, 36, 74, 52, 31, 42}, K = 3
Output : 7
Explanation :
There are seven pairs whose sum is divisible by 3,
i.e, (9, 36), (9,42), (74, 52), (36, 42), (74, 31),
(31, 5) and (5, 52).
Your task :
You don't have to read input or print anything. Your task is to complete the function countKdivPairs() which takes the array, it's size and an integer K as input and returns the count of pairs whose sum is divisible by K.

Expected Time Complexity : O(n)
Expected Auxiliary Space : O(k)

Constraints :
1 <= N <=10^6
1 <= A[i] <= 10^6
1 <= K <= 100

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