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?

Solution:

class Solution {
public:
int singleNumber(vector<int>& nums) {
if(nums.size() == 0) return 0;
for(int i = 1; i < nums.size(); ++i) nums[0] ^= nums[i];

return nums[0];
}
};