Squares of a Sorted Array — LeetCode 977 Python Solution

The problem

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

Input

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

Output

[0,1,9,16,100]

Explanation

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

Python solution

class Solution:
    def sortedSquares(self, nums: List[int]) -> List[int]:
        ans = []
        i, j = 0, len(nums) - 1
        while i <= j:
            a = nums[i] * nums[i]
            b = nums[j] * nums[j]
            if a > b:
                ans.append(a)
                i += 1
            else:
                ans.append(b)
                j -= 1
        return ans[::-1]

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 977. Squares of a Sorted Array is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Two Pointers.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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