136. Single Number (Bit)

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) {
int result = A[0];
int i = 1;
while(i<n)
{
result = A[i] ^ result; //异或，相同为0 不同为1
i++;
}
return result;
}
};