Leetcode 137 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?

方法一：原理同 Leetcode 136 Single Number

var singleNumber = function(nums) {

    var hash = {}

    for(var i=0; i<nums.length; i++)

        if(!hash.hasOwnProperty(nums[i]))

            hash[nums[i]] = 1

        else

            hash[nums[i]] += 1

    for(var x in hash)

        if(hash[x] < 2)

            return Number(x)

}

方法二：Bit Manipulation