class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """

        # slow pointer to keep tracker of the non-target elements
        left = 0

        # fast pointer to find the non-
        for right in range(len(nums)):
            if nums[right]:
                nums[left], nums[right] = nums[right], nums[left]
                left += 1

        return nums


# However note this does not work because you are literally re-assigning the array
# because you are reassigning the array rather than modifying in-place
class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        slow = 0

        for fast in range(len(nums)):
            if nums[fast] != 0:
                nums[slow] = nums[fast]
                slow += 1

        nums = nums[:slow] + (len(nums) - slow)*[0]