[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/

 

 

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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;
};