You are given a non-empty array of integers where every element appears twice except for one.
Return the single element that appears only once.
Examples
Input: nums = [2,2,1] Output: 1
Input: nums = [4,1,2,1,2] Output: 4
Constraints
- 1 <= nums.length <= 30,000
- -30,000 <= nums[i] <= 30,000
- Exactly one element appears once.