Tags: "leetcode", "two-pointers", "array", access_time 1-min read

Squares of a Sorted Array

Created: February 10, 2020 by [lek-tin]

Last updated: February 10, 2020

Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted non-decreasing order.

Example 1

Input: [-4,-1,0,3,10]
Output: [0,1,9,16,100]

Example 2

Input: [-7,-3,2,3,11]
Output: [4,9,9,49,121]

Note

1. 1 <= A.length <= 10000
2. -10000 <= A[i] <= 10000
3. A is sorted in non-decreasing order.

Solution

class Solution:
    def sortedSquares(self, A: List[int]) -> List[int]:
        result = A[:]
        leftPtr, rightPtr = 0, len(A)-1
        i = 0

        while leftPtr <= rightPtr:
            i += 1
            if abs(A[leftPtr]) <= abs(A[rightPtr]):
                result[-i] =  A[rightPtr] * A[rightPtr]
                rightPtr -= 1
            else:
                result[-i] = A[leftPtr] * A[leftPtr]
                leftPtr += 1

        return result