1089. 复写零

from typing import List


class Solution:
    def duplicateZeros(self, arr: List[int]) -> None:
        """
        Do not return anything, modify arr in-place instead.
        """
        l = len(arr)
        i = 0
        while i < l:
            if arr[i] == 0:
                arr.insert(i, 0)
                i += 1

            i += 1

        while len(arr) > l:
            arr.pop()