Find a number where it appears exactly N/2 times

Question

Here is one of my interview question. Given an array of N elements and where an element appears exactly N/2 times and the rest N/2 elements are unique

Answer 1

My Answer was,

1. Divide N elements into [N/3] parts (i.e) each part will have 3 elements.
2. Now compare these 3 elements among each other. - 3 comparisions
3. Atleast one of the part will have two copies of the same element. Hence the number.

Runtime - O(N)