Sort Transformed Array

Problem: Sort Transformed Array

The function's graph is a curve, which is able to be sorted easily with two pointers.

Code in Python:

class Solution(object):
    def sortTransformedArray(self, nums, a, b, c):
        """
        :type nums: List[int]
        :type a: int
        :type b: int
        :type c: int
        :rtype: List[int]
        """
        if a == 0:
            if b == 0: return [c] * len(nums)
            if b > 0: return [b * num + c for num in nums]
            if b < 0: return [b * num + c for num in nums[::-1]]

        res = []
        l, r = 0, len(nums)-1
        while l < r:
            nl, nr = nums[l], nums[r]
            fl, fr = a * nl * nl + b * nl + c, a * nr * nr + b * nr + c
            if fl < fr:
                if a > 0:
                    res.append(fr)
                    r -= 1
                else:
                    res.append(fl)
                    l += 1
            else:
                if a > 0:
                    res.append(fl)
                    l += 1
                else:
                    res.append(fr)
                    r -= 1
        nl = nums[l]
        res.append(a * nl * nl + b * nl + c)

        return res if a < 0 else res[::-1]