Single Number II

Medium

Every element in nums appears exactly three times except for one, which appears once. Return that single element. O(n) time and O(1) extra space.

Example 1

Input:  nums = [2,2,3,2]
Output: 3

Example 2

Input:  nums = [0,1,0,1,0,1,99]
Output: 99

Constraints

• 1 <= nums.length <= 3*10^4
• Each element appears 3x except one which appears once.