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# 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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