0027-remove-element.py

class Solution:
    def removeElement(self, nums: List[int], val: int) -> int:
        k = 0
        for i in range(len(nums)):
            if nums[i] != val:
                nums[k] = nums[i]
                k += 1
        return k

# Optimized solution with the same time and space complexity
class Solution:
    def removeElement(self, nums: List[int], val: int) -> int:
        # Avoid unessary copy operations in a previous solution, when k == i and nums[i] != val 
        # by swapping nums[i] and the last element of the array (nums[n])
        n = len(nums)
        i = 0

        while i < n:
            if nums[i] == val:
                nums[i], nums[n - 1] = nums[n - 1], nums[i]
                n -= 1  # decrement the length of the array by discarding the last element
            else:
                i += 1
        
        return n