Javascript Program to Move all zeroes to end of array (original) (raw)

Last Updated : 19 Sep, 2024

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.

JavaScript `

// A JavaScript program to move all zeroes at the end of array

// Function which pushes all zeros to end of an array. function pushZerosToEnd(arr, n) { let 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 (let i = 0; i < n; i++)
    if (arr[i] != 0)
        arr[count++] = arr[i]; // here count is 
// incremented 

// 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;

}

// Driver code let arr = [1, 9, 8, 4, 0, 0, 2, 7, 0, 6, 0, 9]; let n = arr.length; pushZerosToEnd(arr, n); console.log("Array after pushing all zeros to end of array : "); console.log(arr.join(" "));

`

Output

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

Complexity Analysis:

• **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!