Leetcode Single Number II

Single Number II

Given an array of integers, every element appears three times except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

给定一个数组，其中有一个数字只出现一次，其它数字都出现了三次，找出这个出现一次的数字。要求线性时间复杂度，并且最好不要申请额外的空间（时间复杂度O(n)，空间复杂度O(1)）。

int singleNumber(vector<int>& nums) {    int ones=0, twos=0, remains;    for(int i=0; i<nums.size(); i++)    {        remains = nums[i] & ~twos;        twos = twos & ~nums[i];        twos |= ones & remains;        ones = ones ^ remains;    }    return ones;}