Write a function named countDuplicates that accepts an array of integers and its length as parameters and that returns the number of duplicate values in the array.
A duplicate value is a value that also occurs earlier in the array.
For example, if an array named a contains {1, 4, 2, 4, 7, 1, 1, 9, 2, 3, 4, 1}, then the call of countDuplicates(a, 12) should return 6 because there are three duplicates of the value 1, one duplicate of the value 2, and two duplicates of the value 4.
Constraints:
The array could be empty or could contain only a single element; in such cases, your function should return 0.
Do not modify the contents of the array.
