Bubble Sort On Doubly Linked List

Sort the given doubly linked list using bubble sort. 

Examples: 

Input :  5  4  3  2  1
Output : 1  2  3  4  5

Input : 2  1  3  5  4
Output :1  2  3  4  5

Explanation: As we do in the bubble sort, here also we check elements of two adjacent nodes whether they are in ascending order or not, if not then we swap the element. We do this until every element gets its original position.
In the 1st pass, the largest element gets its original position, and in the 2nd pass 2nd largest element gets its original position and in the 3rd pass, the 3rd largest element gets its original position, and so on. 
And finally, the whole list gets sorted.

Note: If the list is already sorted then it will do only one pass. 

Implementation:

C++

// CPP program to sort a doubly linked list using
// bubble sort
#include <iostream>
using namespace std;

// structure of a node
struct Node {
    int data;
    Node* prev;
    Node* next;
};

/* Function to insert a node at the beginning of a linked list */
void insertAtTheBegin(struct Node **start_ref, int data)
{
    struct Node *ptr1 = new Node;
    ptr1->data = data;
    ptr1->next = *start_ref;
    if (*start_ref != NULL)
       (*start_ref)->prev = ptr1;
    *start_ref = ptr1;
}

/* Function to print nodes in a given linked list */
void printList(struct Node *start)
{
    struct Node *temp = start;
    cout << endl;
    while (temp!=NULL)
    {
        cout << temp->data << " ";
        temp = temp->next;
    }
}

/* Bubble sort the given linked list */
void bubbleSort(struct Node *start)
{
    int swapped, i;
    struct Node *ptr1;
    struct Node *lptr = NULL;

    /* Checking for empty list */
    if (start == NULL)
        return;

    do
    {
        swapped = 0;
        ptr1 = start;

        while (ptr1->next != lptr)
        {
            if (ptr1->data > ptr1->next->data)
            {
                swap(ptr1->data, ptr1->next->data);
                swapped = 1;
            }
            ptr1 = ptr1->next;
        }
        lptr = ptr1;
    }
    while (swapped);
}

int main()
{
    int arr[] = {12, 56, 2, 11, 1, 90};
    int list_size, i;

    /* start with empty linked list */
    struct Node *start = NULL;

    /* Create linked list from the array arr[].
      Created linked list will be 1->11->2->56->12 */
    for (i = 0; i< 6; i++)
        insertAtTheBegin(&start, arr[i]);

    /* print list before sorting */
    printf("\n Linked list before sorting ");
    printList(start);

    /* sort the linked list */
    bubbleSort(start);

    /* print list after sorting */
    printf("\n Linked list after sorting ");
    printList(start);

    return 0;
}

Java

// Java program to sort a doubly linked list using
// bubble sort
class GFG
{

// structure of a node
static class Node
{
    int data;
    Node prev;
    Node next;
};

// Function to insert a node at the beginning of a linked list
static Node insertAtTheBegin( Node start_ref, int data)
{
    Node ptr1 = new Node();
    ptr1.data = data;
    ptr1.next = start_ref;
    if (start_ref != null)
    (start_ref).prev = ptr1;
    start_ref = ptr1;
    return start_ref;
}

// Function to print nodes in a given linked list
static void printList( Node start)
{
    Node temp = start;
    System.out.println();
    while (temp != null)
    {
        System.out.print( temp.data + " ");
        temp = temp.next;
    }
}

// Bubble sort the given linked list
static Node bubbleSort( Node start)
{
    int swapped, i;
    Node ptr1;
    Node lptr = null;

    // Checking for empty list
    if (start == null)
        return null;

    do
    {
        swapped = 0;
        ptr1 = start;

        while (ptr1.next != lptr)
        {
            if (ptr1.data > ptr1.next.data)
            {
                int t = ptr1.data;
                ptr1.data = ptr1.next.data;
                ptr1.next.data = t;
                swapped = 1;
            }
            ptr1 = ptr1.next;
        }
        lptr = ptr1;
    }
    while (swapped != 0);
        return start;
}

// Driver code
public static void main(String args[])
{
    int arr[] = {12, 56, 2, 11, 1, 90};
    int list_size, i;

    // start with empty linked list
    Node start = null;

    // Create linked list from the array arr[].
    //Created linked list will be 1->11->2->56->12
    for (i = 0; i < 6; i++)
        start=insertAtTheBegin(start, arr[i]);

    // print list before sorting
    System.out.printf("\n Linked list before sorting ");
    printList(start);

    // sort the linked list
    start = bubbleSort(start);

    // print list after sorting
    System.out.printf("\n Linked list after sorting ");
    printList(start);
}
}

// This code is contributed by Arnab Kundu

Python3

# Python3 program to sort a doubly linked list using
# bubble sort

# structure of a node
class Node:

    def __init__(self, data):
        self.data = data
        self.prev = None
        self.next = None

''' Function to insert a node at the beginning of a linked list '''
def insertAtTheBegin(start_ref, data):
    ptr1 = Node(data)
    ptr1.data = data;
    ptr1.next = start_ref;
    if (start_ref != None):
       (start_ref).prev = ptr1;
    start_ref = ptr1;
    return start_ref

''' Function to print nodes in a given linked list '''
def printList(start):
    temp = start;
    print()
    while (temp != None):
        print(temp.data, end = ' ')
        temp = temp.next;

''' Bubble sort the given linked list '''
def bubbleSort(start):
    swapped = 0
    lptr = None;

    ''' Checking for empty list '''
    if (start == None):
        return;

    while True:
        swapped = 0;
        ptr1 = start;
        while (ptr1.next != lptr):
            if (ptr1.data > ptr1.next.data):
                ptr1.data, ptr1.next.data = ptr1.next.data, ptr1.data
                swapped = 1;
            ptr1 = ptr1.next;
        lptr = ptr1;
        if swapped == 0:
            break

# Driver code
if __name__=='__main__':

    arr = [12, 56, 2, 11, 1, 90]

    ''' start with empty linked list '''
    start = None;

    ''' Create linked list from the array arr[].
      Created linked list will be 1.11.2.56.12 '''
    for i in range(6):
        start = insertAtTheBegin(start, arr[i]);

    ''' print list before sorting '''
    print("Linked list before sorting ", end = '');
    printList(start);

    ''' sort the linked list '''
    bubbleSort(start);

    ''' print list after sorting '''
    print("\nLinked list after sorting ", end = '');
    printList(start);

    # This code is contributed by rutvik_56

C#

// C# program to sort a doubly linked list using
// bubble sort
using System;

class GFG
{

// structure of a node
public class Node
{
    public int data;
    public Node prev;
    public Node next;
};

// Function to insert a node at the beginning of a linked list
static Node insertAtTheBegin( Node start_ref, int data)
{
    Node ptr1 = new Node();
    ptr1.data = data;
    ptr1.next = start_ref;
    if (start_ref != null)
    (start_ref).prev = ptr1;
    start_ref = ptr1;
    return start_ref;
}

// Function to print nodes in a given linked list
static void printList( Node start)
{
    Node temp = start;
    Console.WriteLine();
    while (temp != null)
    {
        Console.Write( temp.data + " ");
        temp = temp.next;
    }
}

// Bubble sort the given linked list
static Node bubbleSort( Node start)
{
    int swapped;
    Node ptr1;
    Node lptr = null;

    // Checking for empty list
    if (start == null)
        return null;

    do
    {
        swapped = 0;
        ptr1 = start;

        while (ptr1.next != lptr)
        {
            if (ptr1.data > ptr1.next.data)
            {
                int t = ptr1.data;
                ptr1.data = ptr1.next.data;
                ptr1.next.data = t;
                swapped = 1;
            }
            ptr1 = ptr1.next;
        }
        lptr = ptr1;
    }
    while (swapped != 0);
        return start;
}

// Driver code
public static void Main(String []args)
{
    int []arr = {12, 56, 2, 11, 1, 90};
    int i;

    // start with empty linked list
    Node start = null;

    // Create linked list from the array arr[].
    //Created linked list will be 1->11->2->56->12
    for (i = 0; i < 6; i++)
        start=insertAtTheBegin(start, arr[i]);

    // print list before sorting
    Console.Write("\n Linked list before sorting ");
    printList(start);

    // sort the linked list
    start = bubbleSort(start);

    // print list after sorting
    Console.Write("\n Linked list after sorting ");
    printList(start);
}
}

// This code contributed by Rajput-Ji

Javascript

<script>
      // JavaScript program to sort a doubly linked list using
      // bubble sort
      // structure of a node
      class Node {
        constructor() {
          this.data = 0;
          this.next = null;
          this.prev = null;
        }
      }

      // Function to insert a node at the beginning of a linked list
      function insertAtTheBegin(start_ref, data) {
        var ptr1 = new Node();
        ptr1.data = data;
        ptr1.next = start_ref;
        if (start_ref != null) start_ref.prev = ptr1;
        start_ref = ptr1;
        return start_ref;
      }

      // Function to print nodes in a given linked list
      function printList(start) {
        var temp = start;
        document.write("<br>");
        while (temp != null) {
          document.write(temp.data + " ");
          temp = temp.next;
        }
      }

      // Bubble sort the given linked list
      function bubbleSort(start) {
        var swapped;
        var ptr1;
        var lptr = null;

        // Checking for empty list
        if (start == null) return null;

        do {
          swapped = 0;
          ptr1 = start;

          while (ptr1.next != lptr) {
            if (ptr1.data > ptr1.next.data) {
              var t = ptr1.data;
              ptr1.data = ptr1.next.data;
              ptr1.next.data = t;
              swapped = 1;
            }
            ptr1 = ptr1.next;
          }
          lptr = ptr1;
        } while (swapped != 0);
        return start;
      }

      // Driver code
      var arr = [12, 56, 2, 11, 1, 90];
      var i;

      // start with empty linked list
      var start = null;

      // Create linked list from the array arr[].
      //Created linked list will be 1->11->2->56->12
      for (i = 0; i < 6; i++) start = insertAtTheBegin(start, arr[i]);

      // print list before sorting
      document.write("Linked list before sorting ");
      printList(start);

      // sort the linked list
      start = bubbleSort(start);

      // print list after sorting
      document.write("<br> Linked list after sorting ");
      printList(start);

      // This code is contributed by rdtank.
    </script>

Output

 Linked list before sorting 
90 1 11 2 56 12 
 Linked list after sorting 
1 2 11 12 56 90 

Complexity Analysis:

• Time Complexity: O(n²)
• Auxiliary Space: O(1)