1 class Solution: 2     def duplicateZeros(self, arr: List[int]) -> None: 3         """ 4         Do not return anything, modify arr in-place instead. 5         """ 6         n = len(arr) 7         if n > 0: 8             i = 0 9             while i < n - 1:10                 if arr[i] == 0:11                     for j in range(n-2,i,-1):12                         arr[j+1] = arr[j]13                     arr[i+1] = 014                     i += 215                 else:16                     i += 1