弹出一个元素并将相同元素附加到 Python 列表的时间复杂度是多少？

Question

So I know popping an element from an an array is O(n) since you have to shift all the elements over by one. BUT, what if you popped an element AND appended that same element to the back of the array, all in one line. Would this be constant operation O(1) since you don't have to shift anything? Please see my code below with the comment.

def moveZeroes(self, nums: List[int]) -> None:
        index = 0
        zeroes = nums.count(0)
        counter = 0
        while True:
            if counter == zeroes:
                break
            if nums[index] == 0:
                nums.append(nums.pop(index))  # THIS LINE RIGHT HERE
                counter += 1
            else:
                index += 1

Answer 1

1. When you pop any element using its index, you make at most len(array) shifts to reduce the length by 1.

2. You can append an element into an array in O(1) time complexity.

However, when you call nums.append(nums.pop(index)) . It will first do step 1 and then do step 2. So overall, you still do O(n) operations.