Duplicate Zeros in Python

Suppose we have a fixed length array of integers, we have to duplicate each occurrence of zero, shifting the remaining elements to the right side.

Note that elements beyond the length of the original array are not written.

So suppose the array is like [1,0,2,3,0,4,5,0], then after modification it will be [1,0,0,2,3,0,0,4]

To solve this, we will follow these steps −

• copy arr into another array arr2, set i and j as 0
• while i < size of arr −
  • if arr2[i] is zero, then
    • arr[i] := 0
    • increase i by 1
    • if i < size of arr, then arr[i] := 0
  • else arr[i] := arr2[j]
  • increase i and j by 1

Example

Let us see the following implementation to get better understanding −

class Solution(object):
   def duplicateZeros(self, arr):
      """
      :type arr: List[int]
      :rtype: None Do not return anything, modify arr in-place
      instead.
      """
      arr2 = [i for i in arr]
      i=0
      j = 0
      while i < len(arr):
         if not arr2[j]:
            arr[i] = 0
            i+=1
            if i<len(arr):
               arr[i] = 0
         else:
            arr[i] = arr2[j]
         j+=1
         i+=1

Input

[1,0,2,3,0,4,5,0]

Output

[1,0,0,2,3,0,0,4]

Arnab Chakraborty

Published on 16-Jan-2020 12:27:05