Given an array of integers, every element appears twice except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
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1 public class Solution { 2 public int singleNumber(int[] nums) { 3 HashSet<Integer> hs = new HashSet<Integer>(); 4 for(int i=0;i< nums.length;i++){ 5 if(hs.contains(nums[i])) hs.remove(nums[i]); 6 else hs.add(nums[i]); 7 } 8 Iterator<Integer> it = hs.iterator(); 9 return it.next(); 10 } 11 }
不是最优。
原文：http://www.cnblogs.com/guoguolan/p/5390683.html