Non Repeating Numbers

Given an array A containing 2 x N+2 positive numbers, out of which 2 x N numbers exist in pairs whereas the other two number occur exactly once and are distinct. Find the other two numbers.

• Time : O(n)
• Space : O(1)

class Solution
{
public:
    vector<int> singleNumber(vector<int> nums)
    {
        int n = nums.size();
        int mask = 0;
        for(auto& n : nums) {
            mask ^= n;
        }
        mask = mask & (~(mask - 1));
        int a = 0, b = 0;
        vector<int> res;
        for(auto& n : nums) {
            if(mask & n) a ^= n;
            else b ^= n;
        }
        return {min(a,b), max(a,b)};
    }
};