# Python3 Program to Move all zeroes to end of array

• Last Updated : 23 Dec, 2021

Given an array of random numbers, Push all the zero’s of a given array to the end of the array. For example, if the given arrays is {1, 9, 8, 4, 0, 0, 2, 7, 0, 6, 0}, it should be changed to {1, 9, 8, 4, 2, 7, 6, 0, 0, 0, 0}. The order of all other elements should be same. Expected time complexity is O(n) and extra space is O(1).
Example:

```Input :  arr[] = {1, 2, 0, 4, 3, 0, 5, 0};
Output : arr[] = {1, 2, 4, 3, 5, 0, 0};

Input : arr[]  = {1, 2, 0, 0, 0, 3, 6};
Output : arr[] = {1, 2, 3, 6, 0, 0, 0};```

There can be many ways to solve this problem. Following is a simple and interesting way to solve this problem.
Traverse the given array ‘arr’ from left to right. While traversing, maintain count of non-zero elements in array. Let the count be ‘count’. For every non-zero element arr[i], put the element at ‘arr[count]’ and increment ‘count’. After complete traversal, all non-zero elements have already been shifted to front end and ‘count’ is set as index of first 0. Now all we need to do is that run a loop which makes all elements zero from ‘count’ till end of the array.
Below is the implementation of the above approach.

## Python3

 `# Python3 code to move all zeroes``# at the end of array`` ` `# Function which pushes all``# zeros to end of an array.``def` `pushZerosToEnd(arr, n):``    ``count ``=` `0` `# Count of non-zero elements``     ` `    ``# Traverse the array. If element ``    ``# encountered is non-zero, then``    ``# replace the element at index``    ``# 'count' with this element``    ``for` `i ``in` `range``(n):``        ``if` `arr[i] !``=` `0``:``             ` `            ``# here count is incremented``            ``arr[count] ``=` `arr[i]``            ``count``+``=``1``     ` `    ``# Now all non-zero elements have been``    ``# shifted to front and 'count' is set``    ``# as index of first 0. Make all ``    ``# elements 0 from count to end.``    ``while` `count < n:``        ``arr[count] ``=` `0``        ``count ``+``=` `1``         ` `# Driver code``arr ``=` `[``1``, ``9``, ``8``, ``4``, ``0``, ``0``, ``2``, ``7``, ``0``, ``6``, ``0``, ``9``]``n ``=` `len``(arr)``pushZerosToEnd(arr, n)``print``(``"Array after pushing all zeros to end of array:"``)``print``(arr)`` ` `# This code is contributed by "Abhishek Sharma 44"`

Output:

```Array after pushing all zeros to end of array :
1 9 8 4 2 7 6 9 0 0 0 0```

Time Complexity: O(n) where n is number of elements in input array.
Auxiliary Space: O(1)

Please refer complete article on Move all zeroes to end of array for more details!

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