Squares of a Sorted Array

class Solution {
public:
    vector<int> sortedSquares(vector<int>& nums) {
        int lower = lower_bound(nums.begin(), nums.end(), 0) - nums.begin(), r, l, n = nums.size();
        r = lower, l = lower - 1;
        vector < int > ans;
        while(l >= 0 || r < n){
            if(l < 0) ans.push_back(nums[r] * nums[r]), r++;
            else if(r >= n) ans.push_back(nums[l] * nums[l]), l--;
            else {
                if((nums[l] * nums[l]) > (nums[r] * nums[r]))
                    ans.push_back(nums[r] * nums[r]), r++;
                else
                    ans.push_back(nums[l] * nums[l]), l--;
            }
        }
        return ans;
    }
};