找到单独的数字 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?

class Solution {
public:
    int singleNumber(int A[], int n) {
        for(int i = 1; i < n; ++i){
		   A[0] ^= A[i];
	    }
	    return A[0];
    }
};

异或在这里就完美演绎了，所有数字在计算机都是0和1，相同的都将消失，留下的就是那个Single Number，我很喜欢这道题。

http://www.waitingfy.com/archives/925