[leetcode]Single Number

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?

解题思路：a ^ a = 0; 0 ^ a = a;

class Solution {
public:
int singleNumber(int A[], int n) {
// Note: The Solution object is instantiated only once and is reused by each test case.
if(n == 1) return A[0];

int rint = A[0];
for(int i = 1; i < n; i++){
rint ^= A[i];
}
return rint;
}
};