Squares of a Sorted Array

Description

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(javascript)

/** Two Pointers O(n)
 * @param {number[]} A
 * @return {number[]}
 */
const sortedSquares = function (A) {
  const result = []
  let left = 0
  let right = A.length - 1
  while (left <= right) {
    const leftSquare = A[left] * A[left]
    const rightSquare = A[right] * A[right]
    if (leftSquare < rightSquare) {
      result.push(rightSquare)
      right -= 1
    } else {
      result.push(leftSquare)
      left += 1
    }
  }
  return result.reverse()
}