You are given an integer array nums with the following properties:
nums.length == 2 * n
.- nums contains n + 1 unique elements.
- Exactly one element of nums is repeated n times. Return the element that is repeated n times.
Input: nums = [1,2,3,3]
Output: 3
Input: nums = [2,1,2,5,3,2]
Output: 2
Input: nums = [5,1,5,2,5,3,5,4]
Output: 5