Javascript Program to Move all zeroes to end of array
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.
// 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!
