Open In App

Move all zeroes to end of array using Two-Pointers

Last Updated : 25 May, 2021
Improve
Improve
Like Article
Like
Save
Share
Report

Given an array of random numbers, Push all the zero’s of the given array to the end of the array. For example, if the given arrays is {1, 0, 2, 6, 0, 4}, it should be changed to {1, 2, 6, 4, 0, 0}. The order of all other elements should be the same.
Examples: 
 

Input: arr[]={8, 9, 0, 1, 2, 0, 3}
Output: arr[]={8, 9, 1, 2, 3, 0, 0}
Explanation: 
Swap {0 ,1} -> Resulting array {8, 9, 1, 0, 2, 0, 3}
Swap {0 ,2} -> Resulting array {8, 9, 1, 2, 0, 0, 3}
Swap {0 ,3} -> Final array {8, 9, 1, 2, 3, 0, 0}

Input: arr[]={4, 5, 0, 0, 0, 0, 6, 7}
Output: arr[]={4, 5, 6, 7, 0, 0, 0, 0}

 

Approach: 
 

  1. Iterate the array from 0 to N
     
  2. Keep two pointers, one for zero elements and other for non-zero elements. 
     
  3. Swap every zero elements with the non-zero element that comes just after it. 
     

 

C




// C implementation to move all zeroes at
// the end of array
#include<stdio.h>
 
// Function to move all zeroes at
// the end of array
void moveZerosToEnd(int arr[], int n)
{
    int j=0, temp, i;
     
    // Traverse the array. If arr[i] is
    // non-zero and arr[j] is zero,
    // then swap both the element
    for(i=0;i<n;i++)
    {
        if(arr[i]!=0 && arr[j]==0)
            {
             temp=arr[i];
             arr[i]=arr[j];
             arr[j]=temp;
            }
        if(arr[j]!=0)
            j+=1;
    }
}
 
// Function to print the array elements
void printArray(int arr[], int n)
{
    for (int i = 0; i < n; i++)
         printf("%d ", arr[i]);
}
 
// Driver Code
int main()
{
    int arr[] = {8, 9, 0, 1, 2, 0, 3};
    int n = sizeof(arr) / sizeof(arr[0]);
 
    printf("Original array: ");
    printArray(arr, n);
 
    moveZerosToEnd(arr, n);
 
    printf("\nModified array: ");
    printArray(arr, n);
 
    return 0;
}


C++




// C++ implementation to move all zeroes at
// the end of array
#include <iostream>
using namespace std;
 
// Function to move all zeroes at
// the end of array
void moveZerosToEnd(int arr[], int n)
{
    int j=0, temp, i;
     
    // Traverse the array. If arr[i] is
    // non-zero and arr[j] is zero,
    // then swap both the element
    for(i=0;i<n;i++)
    {
        if(arr[i]!=0 && arr[j]==0)
            {
             swap(arr[i],arr[j]);
            }
        if(arr[j]!=0)
            j+=1;
    }
}
 
// Function to print the array elements
void printArray(int arr[], int n)
{
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
}
 
// Driver Code
int main()
{
    int arr[] = {8, 9, 0, 1, 2, 0, 3};
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << "Original array: ";
    printArray(arr, n);
 
    moveZerosToEnd(arr, n);
 
    cout << "\nModified array: ";
    printArray(arr, n);
 
    return 0;
}


Java




// Java implementation to move all zeroes at
// the end of array
 
class GFG {
 
    // Function to move all zeroes at
    // the end of array
    static void moveZerosToEnd(int arr[], int n) {
        int j = 0, i;
 
        // Traverse the array. If arr[i] is
        // non-zero and arr[j] is zero,
        // then swap both the element
        for (i = 0; i < n; i++) {
            if (arr[i] != 0 && arr[j] == 0) {
                arr = swap(arr, i, j);
            }
            if (arr[j] != 0)
                j += 1;
        }
    }
 
    static int[] swap(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
        return arr;
    }
 
    // Function to print the array elements
    static void printArray(int arr[], int n) {
        for (int i = 0; i < n; i++)
            System.out.print(arr[i] + " ");
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        int arr[] = { 8, 9, 0, 1, 2, 0, 3 };
        int n = arr.length;
 
        System.out.print("Original array: ");
        printArray(arr, n);
 
        moveZerosToEnd(arr, n);
 
        System.out.print("\nModified array: ");
        printArray(arr, n);
 
    }
}
 
// This code is contributed by 29AjayKumar


Python3




# Python3 implementation to move all zeroes at
# the end of array
 
# Function to move all zeroes at
# the end of array
def moveZerosToEnd(nums):
    j = 0
     
    for i in range(len(nums)):
        if nums[i]!= 0 and nums[j]== 0:
            nums[i], nums[j]= nums[j], nums[i]
        if nums[j]!= 0:
            j+= 1
     
 
 
# Function to print the array elements
def printArray(arr, n):
 
    for i in range(0, n):
        print(arr[i],end=" ")
 
 
# Driver program to test above
arr = [8, 9, 0, 1, 2, 0, 3]
n = len(arr)
 
print("Original array:", end=" ")
printArray(arr, n)
 
moveZerosToEnd(arr)
 
print("\nModified array: ", end=" ")
printArray(arr, n)


C#




// C# implementation to move all zeroes
// at the end of array
using System;
 
class GFG{
 
// Function to move all zeroes
// at the end of array
static void moveZerosToEnd(int []arr, int n)
{
    int j = 0, i;
 
    // Traverse the array. If arr[i]
    // is non-zero and arr[j] is zero,
    // then swap both the element
    for(i = 0; i < n; i++)
    {
       if (arr[i] != 0 && arr[j] == 0)
       {
           arr = swap(arr, i, j);
       }
       if (arr[j] != 0)
           j += 1;
    }
}
 
static int[] swap(int[] arr, int i, int j)
{
    int temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
    return arr;
}
 
// Function to print the array elements
static void printArray(int []arr, int n)
{
    for(int i = 0; i < n; i++)
       Console.Write(arr[i] + " ");
}
 
// Driver Code
public static void Main(String[] args)
{
    int []arr = { 8, 9, 0, 1, 2, 0, 3 };
    int n = arr.Length;
 
    Console.Write("Original array: ");
    printArray(arr, n);
 
    moveZerosToEnd(arr, n);
 
    Console.Write("\nModified array: ");
    printArray(arr, n);
}
}
 
// This code is contributed by 29AjayKumar


Javascript




<script>
 
// JavaScript implementation to move all zeroes at
// the end of array
 
// Function to move all zeroes at
// the end of array
function moveZerosToEnd(arr, n)
{
    let j=0, temp, i;
     
    // Traverse the array. If arr[i] is
    // non-zero and arr[j] is zero,
    // then swap both the element
    for(i=0;i<n;i++)
    {
        if(arr[i]!=0 && arr[j]==0)
            {
                let temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        if(arr[j]!=0)
            j+=1;
    }
}
 
// Function to print the array elements
function printArray(arr, n)
{
    for (let i = 0; i < n; i++)
        document.write(arr[i] + " ");
}
 
// Driver Code
    let arr = [8, 9, 0, 1, 2, 0, 3];
    let n = arr.length;
 
    document.write("Original array: ");
    printArray(arr, n);
 
    moveZerosToEnd(arr, n);
 
    document.write("<br>Modified array: ");
    printArray(arr, n);
 
 
// This code is contributed by Surbhi Tyagi.
 
</script>


Output: 

Original array: 8 9 0 1 2 0 3 
Modified array: 8 9 1 2 3 0 0

 

Time Complexity: O(N). 
Auxiliary Space: O(1)
 



Like Article
Suggest improvement
Previous
Next
Share your thoughts in the comments

Similar Reads