Squares of a Sorted Array

Squares of a Sorted Array (Easy)

Link : https://leetcode.com/problems/squares-of-a-sorted-array/

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order.

 

Example 1:

Input: nums = [-4,-1,0,3,10]

Output: [0,1,9,16,100]

Explanation: After squaring, the array becomes [16,1,0,9,100].

After sorting, it becomes [0,1,9,16,100].

Example 2:

Input: nums = [-7,-3,2,3,11]

Output: [4,9,9,49,121]

 

Constraints:

1 <= nums.length <= 104

-104 <= nums[i] <= 104

nums is sorted in non-decreasing order.

 

Follow up: Squaring each element and sorting the new array is very trivial, could you find an O(n) solution using a different approach?

Solution (C++) :

    vector<int> sortedSquares(vector<int>& nums) {
        int n = nums.size();
        int start=0;
        int end=n-1;
        
        vector <int> res(n);
        int pos = n-1;
        
        while(start <= end)
        {
            if(abs(nums[start]) < abs(nums[end])) {
                res[pos--] = nums[end] * nums[end];
                end--;
            } else{
                res[pos--] = nums[start] * nums[start];
                start++;
            }
        }
        
        return res;
    }