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Insert value in sorted way in a sorted doubly linked list

  • Difficulty Level : Easy
  • Last Updated : 12 May, 2021

Given a sorted doubly linked list and a value to insert, write a function to insert the value in sorted way.
Initial doubly linked list
 

Doubly Linked List after insertion of 9
 

Algorithm: 
Let input doubly linked list is sorted in increasing order. 
New node passed to the function contains data in the data part and previous and next link are set to NULL.



sortedInsert(head_ref, newNode)
      if (head_ref == NULL)
      head_ref = newNode
        
      else if head_ref->data >= newNode->data
          newNode->next = head_ref
      newNode->next->prev = newNode
      head_ref = newNode    
        
      else
      Initialize current = head_ref
      while (current->next != NULL and
               current->next->data < newNode->data)
        current = current->next
        
      newNode->next = current->next
      if current->next != NULL
        newNode->next->prev = newNode
            
          current->next = newNode
      newNode->prev = current

C++




// C++ implementation to insert value in sorted way
// in a sorted doubly linked list
#include <bits/stdc++.h>
 
using namespace std;
 
// Node of a doubly linked list
struct Node {
    int data;
    struct Node* prev, *next;
};
 
// function to create and return a new node
// of a doubly linked list
struct Node* getNode(int data)
{
    // allocate node
    struct Node* newNode =
        (struct Node*)malloc(sizeof(struct Node));
 
    // put in the data
    newNode->data = data;
    newNode->prev = newNode->next = NULL;
    return newNode;
}
 
// function to insert a new node in sorted way in
// a sorted doubly linked list
void sortedInsert(struct Node** head_ref, struct Node* newNode)
{
    struct Node* current;
 
    // if list is empty
    if (*head_ref == NULL)
        *head_ref = newNode;
 
    // if the node is to be inserted at the beginning
    // of the doubly linked list
    else if ((*head_ref)->data >= newNode->data) {
        newNode->next = *head_ref;
        newNode->next->prev = newNode;
        *head_ref = newNode;
    }
 
    else {
        current = *head_ref;
 
        // locate the node after which the new node
        // is to be inserted
        while (current->next != NULL &&
               current->next->data < newNode->data)
            current = current->next;
 
        /* Make the appropriate links */
        newNode->next = current->next;
 
        // if the new node is not inserted
        // at the end of the list
        if (current->next != NULL)
            newNode->next->prev = newNode;
 
        current->next = newNode;
        newNode->prev = current;
    }
}
 
// function to print the doubly linked list
void printList(struct Node* head)
{
    while (head != NULL) {
        cout << head->data << " ";
        head = head->next;
    }
}
 
// Driver program to test above
int main()
{
    /* start with the empty doubly linked list */
    struct Node* head = NULL;
 
    // insert the following nodes in sorted way
    struct Node* new_node = getNode(8);
    sortedInsert(&head, new_node);
    new_node = getNode(5);
    sortedInsert(&head, new_node);
    new_node = getNode(3);
    sortedInsert(&head, new_node);
    new_node = getNode(10);
    sortedInsert(&head, new_node);
    new_node = getNode(12);
    sortedInsert(&head, new_node);
    new_node = getNode(9);
    sortedInsert(&head, new_node);
 
    cout << "Created Doubly Linked Listn";
    printList(head);
    return 0;
}

Java




// Java implementation to insert value in sorted way
// in a sorted doubly linked list
import java.io.*;
import java.util.*;
 
// Node of a doubly linked list
class Node
{
    int data;
    Node next, prev;
}
 
class GFG
{
 
    // function to create and return a new node
    // of a doubly linked list
    static Node getNode(int data)
    {
            // allocate node
            Node newNode = new Node();
 
            // put in the data
            newNode.data = data;
            newNode.prev = newNode.next = null;
            return newNode;
 
    }
 
    // function to insert a new node in sorted way in
    // a sorted doubly linked list
    static Node sortedInsert(Node head, Node newNode)
    {
            Node current;
 
            // if list is empty
            if (head == null)
                head = newNode;
 
            // if the node is to be inserted at the beginning
            // of the doubly linked list
            else if (head.data >= newNode.data)
            {
                newNode.next = head;
                newNode.next.prev = newNode;
                head = newNode;
            }
 
            else
            {
                current = head;
 
                // locate the node after which the new node
                // is to be inserted
                while (current.next != null &&
                        current.next.data < newNode.data)
                    current = current.next;
 
                /* Make the appropriate links */
                newNode.next = current.next;
 
                // if the new node is not inserted
                // at the end of the list
                if (current.next != null)
                    newNode.next.prev = newNode;
 
                current.next = newNode;
                newNode.prev = current;
             
            }
            return head;
    }
 
    // function to print the doubly linked list
    static void printList(Node head)
    {
            while (head != null)
            {
                    System.out.print(head.data + " ");
                    head = head.next;
            }
 
    }
 
    // Driver code
    public static void main(String args[])
    {
            /* start with the empty doubly linked list */
            Node head = null;
 
            // insert the following nodes in sorted way
            Node new_node = getNode(8);
            head = sortedInsert(head, new_node);
            new_node = getNode(5);
            head = sortedInsert(head, new_node);
            new_node = getNode(3);
            head = sortedInsert(head, new_node);
            new_node = getNode(10);
            head = sortedInsert(head, new_node);
            new_node = getNode(12);
            head = sortedInsert(head, new_node);
            new_node = getNode(9);
            head = sortedInsert(head, new_node);
 
            System.out.println("Created Doubly Linked List");
            printList(head);
    }
}
 
// This code is contributed by rachana soma

Python3




# Python3 implementation to insert
# value in sorted way in a sorted
# doubly linked list
 
# Node of a doubly linked list
class Node:
 
    # Constructor to initialize
    # the node object
    def __init__(self, data):
         
        self.data = data
        self.next = None
        self.prev = None
 
class DoublyLinkedList:
 
    # Function to initialize head
    def __init__(self):
         
        self.head = None
 
    # Function to create and return a
    # new node of a doubly linked list
    def getNode(self, data):
         
        return Node(data)
 
    # Function to insert a new node in
    # sorted way in a sorted doubly linked list
    def sortedInsert(self, data):
         
        new_node = self.getNode(data)
 
        # If the list is empty
        if self.head is None:
            self.head = new_node
         
        # If the node is to be inserted at 
        # the beginning of the doubly linked list
        elif self.head.data >= new_node.data:
            new_node.next = self.head
            new_node.next.prev = new_node
            self.head = new_node
        else:
            current = self.head
 
            # Locate the node after which
            # the new node  is to be inserted
            while ((current.next is not None) and
                   (current.next.data < new_node.data)):
                current = current.next
     
            # Make the appropriate links
            new_node.next = current.next
 
            # If the new node is not inserted
            # at the end of the list
            if current.next is not None:
                new_node.next.prev = new_node
 
            current.next = new_node
            new_node.prev = current
     
    # Function to print the doubly linked list
    def printList(self):
 
        node = self.head
        while node:
            print(str(node.data), end = " ")
            node = node.next
 
# Driver code
if __name__ == '__main__':
 
    # Insert the following nodes
    # in sorted way
    llist = DoublyLinkedList()
    llist.sortedInsert(8)
    llist.sortedInsert(5)
    llist.sortedInsert(3)
    llist.sortedInsert(10)
    llist.sortedInsert(12)
    llist.sortedInsert(9)
     
    print("Created Doubly Linked List")
    llist.printList()
 
# This code is contributed by Siddhartha Pramanik

C#




// C# implementation to insert value in sorted way
// in a sorted doubly linked list
using System;
 
// Node of a doubly linked list
public class Node
{
    public int data;
    public Node next, prev;
}
 
class GFG
{
 
    // function to create and return a new node
    // of a doubly linked list
    static Node getNode(int data)
    {
        // allocate node
        Node newNode = new Node();
 
        // put in the data
        newNode.data = data;
        newNode.prev = newNode.next = null;
        return newNode;
 
    }
 
    // function to insert a new node in sorted way in
    // a sorted doubly linked list
    static Node sortedInsert(Node head, Node newNode)
    {
        Node current;
 
        // if list is empty
        if (head == null)
            head = newNode;
 
        // if the node is to be inserted at the beginning
        // of the doubly linked list
        else if (head.data >= newNode.data)
        {
            newNode.next = head;
            newNode.next.prev = newNode;
            head = newNode;
        }
 
        else
        {
            current = head;
 
            // locate the node after which the new node
            // is to be inserted
            while (current.next != null &&
                    current.next.data < newNode.data)
                current = current.next;
 
            /* Make the appropriate links */
            newNode.next = current.next;
 
            // if the new node is not inserted
            // at the end of the list
            if (current.next != null)
                newNode.next.prev = newNode;
 
            current.next = newNode;
            newNode.prev = current;
         
        }
        return head;
    }
 
    // function to print the doubly linked list
    static void printList(Node head)
    {
        while (head != null)
        {
                Console.Write(head.data + " ");
                head = head.next;
        }
 
    }
 
    // Driver code
    public static void Main(String []args)
    {
        /* start with the empty doubly linked list */
        Node head = null;
 
        // insert the following nodes in sorted way
        Node new_node = getNode(8);
        head = sortedInsert(head, new_node);
        new_node = getNode(5);
        head = sortedInsert(head, new_node);
        new_node = getNode(3);
        head = sortedInsert(head, new_node);
        new_node = getNode(10);
        head = sortedInsert(head, new_node);
        new_node = getNode(12);
        head = sortedInsert(head, new_node);
        new_node = getNode(9);
        head = sortedInsert(head, new_node);
 
        Console.WriteLine("Created Doubly Linked List");
        printList(head);
    }
}
 
// This code is contributed by Arnab Kundu

Javascript




<script>
// javascript implementation to insert value in sorted way
// in a sorted doubly linked list
// Node of a doubly linked list
class Node
{
constructor()
{
     this.data = 0;
     this.next = null, this.prev = null;
     }
}
    // function to create and return a new node
    // of a doubly linked list
    function getNode(data)
    {
     
        // allocate node
         newNode = new Node();
 
        // put in the data
        newNode.data = data;
        newNode.prev = newNode.next = null;
        return newNode;
 
    }
 
    // function to insert a new node in sorted way in
    // a sorted doubly linked list
    function sortedInsert( head,  newNode)
    {
        var current;
 
        // if list is empty
        if (head == null)
            head = newNode;
 
        // if the node is to be inserted at the beginning
        // of the doubly linked list
        else if (head.data >= newNode.data)
        {
            newNode.next = head;
            newNode.next.prev = newNode;
            head = newNode;
        }
 
        else {
            current = head;
 
            // locate the node after which the new node
            // is to be inserted
            while (current.next != null && current.next.data < newNode.data)
                current = current.next;
 
            /* Make the appropriate links */
            newNode.next = current.next;
 
            // if the new node is not inserted
            // at the end of the list
            if (current.next != null)
                newNode.next.prev = newNode;
 
            current.next = newNode;
            newNode.prev = current;
 
        }
        return head;
    }
 
    // function to prvar the doubly linked list
    function printList( head) {
        while (head != null) {
            document.write(head.data + " ");
            head = head.next;
        }
 
    }
 
    // Driver code
     
        /* start with the empty doubly linked list */
         head = null;
 
        // insert the following nodes in sorted way
         new_node = getNode(8);
        head = sortedInsert(head, new_node);
        new_node = getNode(5);
        head = sortedInsert(head, new_node);
        new_node = getNode(3);
        head = sortedInsert(head, new_node);
        new_node = getNode(10);
        head = sortedInsert(head, new_node);
        new_node = getNode(12);
        head = sortedInsert(head, new_node);
        new_node = getNode(9);
        head = sortedInsert(head, new_node);
 
        document.write("Created Doubly Linked List<br/>");
        printList(head);
 
// This code is contributed by umadevi9616
</script>

Output:

Created Doubly Linked List
3 5 8 9 10 12

Time Complexity: O(n)
This article is contributed by Ayush Jauhari. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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