LeetCode:Single Number

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?

这题首先看到要求线性时间复杂度，觉得排序肯定没戏，后来自己折腾还是先用的排序，果然超时。最后参考了别人的代码，是用位运算解决的。没用过位运算，翻了《C Primer Plus》第15章位操作，恶补。

 1 class Solution{
 2 public:
 3     int singleNumber(int A[],int n){
 4         int i,bit=0;
 5         if(n<0)
 6         {
 7             return -1;
 8         }
 9         for(i=0;i<n;i++)
10         {
11             bit^=A[i];
12         }
13         return bit;
14     }
15 };

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LeetCode:Single Number

原文：http://www.cnblogs.com/levicode/p/3856503.html