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
原文：http://www.cnblogs.com/lilixu/p/4589935.html