[LeetCode][JavaScript]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?

https://leetcode.com/problems/single-number-ii/

这种位运算的题超越了我的三观，根本不可能。

https://leetcode.com/discuss/857/constant-space-solution

三个变量分别代表出现了几次。

到最后出现三次的会在threes里，ones里就是结果。

/**
* @param {number[]} nums
* @return {number}
*/
var singleNumber = function(nums) {
var ones = 0, twos = 0, threes = 0;
for(var i = 0; i < nums.length; i++){
twos |= ones & nums[i];
ones ^= nums[i];
threes = ones & twos;
ones &= ~threes;
twos &= ~threes;
}
return ones;
};