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[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?

异或即可处理,而且,不仅能处理两次的情况,只要出现偶数次,都可以清零。

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