[LeetCode][C++] #137. Single Number II

[Medium][Question]:

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.

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 * 104
• -231 <= nums[i] <= 231 - 1
• Each element in nums appears exactly three times except for one element which appears once.

Follow up: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

My Solution[C++]:

[Ideas]: 用Bit-wise Operation，紀錄每個位元出現過的次數，再個別除3取餘數。