squares-of-a-sorted-array

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Description

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(Python)

class Solution:
    def sortedSquares(self, nums: List[int]) -> List[int]:
        n =len(nums)
        left = 0
        right = n-1
        square = 0
        result = [0] * n
        for i in range(n-1, -1, -1):
            if abs(nums[left]) < abs(nums[right]):
                square = nums[right]
                right -= 1
            else:
                square = nums[left]
                left += 1
            result[i] = square * square
        return result