# Insertion in Doubly Circular Linked List

Last Updated : 13 Nov, 2023

Circular Doubly Linked List has properties of both doubly linked list and circular linked list in which two consecutive elements are linked or connected by the previous and next pointer and the last node points to the first node by the next pointer and also the first node points to the last node by the previous pointer.

Following is the representation of a Circular doubly linked list node in C/C++:

## C++

 static class node {   int data;     // pointer to next node   node next;     // pointer to prev node   node prev; }    // This code is contributed by Yash Agarwal(yashagarwal2852002)

## C

 // Structure of the node struct node {     int data;       // Pointer to next node     struct node* next;       // Pointer to previous node     struct node* prev; };

## Java

 class Node {     int data;       // Pointer to the next node     Node next;       // Pointer to the previous node     Node prev; }

## Python

 class Node:     def __init__(self):         # Data in the node         self.data = None           # Pointer to the next node         self.next = None           # Pointer to the previous node         self.prev = None

## C#

 public class Node {     public int Data     {         get;         set;     }     public Node Next     {         get;         set;     }     public Node Prev     {         get;         set;     } }   public class DoublyLinkedList {     // The Doubly Linked List can be implemented here.     // You can create instances of Node to build your list. }

## Javascript

 class Node {     constructor(data) {         this.data = data;  // Data stored in the node         this.next = null;  // Pointer to the next node         this.prev = null;  // Pointer to the previous node     } }

## Insertion in Circular Doubly Linked List:

### 1. Insertion at the end of the list or in an empty list:

A node(Say N) is inserted with data = 5. So, the previous pointer of N points to N and the next pointer of N also points to N. But now start pointer points to the first node of the list.

Insertion in an empty list

### 2. List initially contains some nodes, start points to the first node of the List:

A node(Say M) is inserted with data = 7, so the previous pointer of M points to the last node, the next pointer of M points to the first node and the last node’s next pointer points to this M node, and first node’s previous pointer points to this M node.

Insertion at the end of list

Below is the implementation of the above operations:

## C++

 // Function to insert at the end void insertEnd(struct Node** start, int value) {     // If the list is empty, create a single node     // circular and doubly list     if (*start == NULL) {         struct Node* new_node = new Node;         new_node->data = value;         new_node->next = new_node->prev = new_node;         *start = new_node;         return;     }       // If list is not empty       /* Find last node */     Node* last = (*start)->prev;       // Create Node dynamically     struct Node* new_node = new Node;     new_node->data = value;       // Start is going to be next of new_node     new_node->next = *start;       // Make new node previous of start     (*start)->prev = new_node;       // Make last previous of new node     new_node->prev = last;       // Make new node next of old last     last->next = new_node; }

## Java

 // Function to insert at the end static void insertEnd(int value) {       // If the list is empty, create a single     // node circular and doubly list     if (start == null) {         Node new_node = new Node();         new_node.data = value;         new_node.next = new_node.prev = new_node;         start = new_node;         return;     }       // If list is not empty       // Find last node     Node last = (start).prev;       // Create Node dynamically     Node new_node = new Node();     new_node.data = value;       // Start is going to be     // next of new_node     new_node.next = start;       // Make new node previous of start     (start).prev = new_node;       // Make last previous of new node     new_node.prev = last;       // Make new node next of old last     last.next = new_node; }   // This code is contributed by rutvik_56

## Python3

 # Function to insert at the end def insertEnd(value):     global start       # If the list is empty, create a     # single node circular and doubly list     if (start == None):           new_node = Node(0)         new_node.data = value         new_node.next = new_node.prev = new_node         start = new_node         return       # If list is not empty       # Find last node */     last = (start).prev       # Create Node dynamically     new_node = Node(0)     new_node.data = value       # Start is going to be next of new_node     new_node.next = start       # Make new node previous of start     (start).prev = new_node       # Make last previous of new node     new_node.prev = last       # Make new node next of old last     last.next = new_node       # This code is contributed by shivanisinghss2110

## C#

 // Function to insert at the end static void insertEnd(int value) {     Node new_node;       // If the list is empty, create a single node     // circular and doubly list     if (start == null) {         new_node = new Node();         new_node.data = value;         new_node.next = new_node.prev = new_node;         start = new_node;         return;     }       // If list is not empty       /* Find last node */     Node last = (start).prev;       // Create Node dynamically     new_node = new Node();     new_node.data = value;       // Start is going to be next of new_node     new_node.next = start;       // Make new node previous of start     (start).prev = new_node;       // Make last previous of new node     new_node.prev = last;       // Make new node next of old last     last.next = new_node; }   // This code is contributed by Pratham76

## Javascript

 // Function to insert at the end function insertEnd(value) {           // If the list is empty, create a single       // node circular and doubly list     if (start == null)     {         var new_node = new Node();         new_node.data = value;         new_node.next = new_node.prev = new_node;         start = new_node;         return;     }        // If list is not empty        // Find last node     var last = (start).prev;        // Create Node dynamically     var new_node = new Node();     new_node.data = value;        // Start is going to be       // next of new_node     new_node.next = start;        // Make new node previous of start     (start).prev = new_node;        // Make last previous of new node     new_node.prev = last;        // Make new node next of old last     last.next = new_node; }     // This code contributed by aashish1995

### 3. Insertion at the beginning of the list:

To insert a node at the beginning of the list, create a node(Say T) with data = 5, T next pointer points to the first node of the list, T previous pointer points to the last node of the list, last node’s next pointer points to this T node, first node’s previous pointer also points this T node and at last don’t forget to shift ‘Start’ pointer to this T node.

Insertion at the beginning of the list

Below is the implementation of the above operation:

## C++

 // Function to insert Node at the beginning // of the List, void insertBegin(struct Node** start, int value) {     // Pointer points to last Node     struct Node* last = (*start)->prev;       struct Node* new_node = new Node;     new_node->data = value; // Inserting the data       // setting up previous and next of new node     new_node->next = *start;     new_node->prev = last;       // Update next and previous pointers of start     // and last.     last->next = (*start)->prev = new_node;       // Update start pointer     *start = new_node; }

## Java

 // Function to insert Node at the beginning // of the List, static void insertBegin(int value) {     // Pointer points to last Node     Node last = (start).prev;       Node new_node = new Node();     new_node.data = value; // Inserting the data       // setting up previous and next of new node     new_node.next = start;     new_node.prev = last;       // Update next and previous pointers of start     // and last.     last.next = (start).prev = new_node;       // Update start pointer     start = new_node; }   // this code is contributed by shivanisinghss2110

## Python3

 # Function to insert Node at the beginning # of the List,     def insertBegin(value):     global start       # Pointer points to last Node     last = (start).prev       new_node = Node(0)     new_node.data = value  # Inserting the data       # setting up previous and     # next of new node     new_node.next = start     new_node.prev = last       # Update next and previous pointers     # of start and last.     last.next = (start).prev = new_node       # Update start pointer     start = new_node       # This code is contributed by shivanisinghss2110

## C#

 // Function to insert Node at the beginning // of the List, static void insertBegin(int value) {       // Pointer points to last Node     Node last = (start).prev;       Node new_node = new Node();     new_node.data = value; // Inserting the data       // setting up previous and next of new node     new_node.next = start;     new_node.prev = last;       // Update next and previous pointers of start     // and last.     last.next = (start).prev = new_node;       // Update start pointer     start = new_node; }   // This code is contributed by shivanisinghss2110

## Javascript

 // Function to insert Node at the beginning       // of the List,       function insertBegin(value) {         // Pointer points to last Node         var last = start.prev;           var new_node = new Node();         new_node.data = value; // Inserting the data           // setting up previous and next of new node         new_node.next = start;         new_node.prev = last;           // Update next and previous pointers of start         // and last.         last.next = start.prev = new_node;           // Update start pointer         start = new_node;       }               // This code is contributed by shivanisinghss2110

### 4. Insertion in between the nodes of the list:

To insert a node in between the list, two data values are required one after which new node will be inserted and another is the data of the new node.

Insertion in between other nodes

Below is the implementation of the above operation:

## C++

 // Function to insert node with value as value1. // The new node is inserted after the node with // with value2 void insertAfter(struct Node** start, int value1,                  int value2) {     struct Node* new_node = new Node;     new_node->data = value1; // Inserting the data       // Find node having value2 and next node of it     struct Node* temp = *start;     while (temp->data != value2)         temp = temp->next;     struct Node* next = temp->next;       // insert new_node between temp and next.     temp->next = new_node;     new_node->prev = temp;     new_node->next = next;     next->prev = new_node; }

## Java

 // Function to insert node with value as value1. // The new node is inserted after the node with // with value2 static void insertAfter(int value1, int value2) {     Node new_node = new Node();     new_node.data = value1; // Inserting the data       // Find node having value2 and next node of it     Node temp = start;     while (temp.data != value2)         temp = temp.next;     Node next = temp.next;       // insert new_node between temp and next.     temp.next = new_node;     new_node.prev = temp;     new_node.next = next;     next.prev = new_node; }   // this code is contributed by shivanisinghss2110

## Python3

 # Function to insert node with value as value1. # The new node is inserted after the node with # with value2     def insertAfter(value1, value2):     global start     new_node = Node(0)     new_node.data = value1  # Inserting the data       # Find node having value2 and     # next node of it     temp = start     while (temp.data != value2):         temp = temp.next     next = temp.next       # insert new_node between temp and next.     temp.next = new_node     new_node.prev = temp     new_node.next = next     next.prev = new_node   # this code is contributed by shivanisinghss2110

## C#

 // Function to insert node with value as value1. // The new node is inserted after the node with // with value2 static void insertAfter(int value1, int value2) {     Node new_node = new Node();     new_node.data = value1; // Inserting the data       // Find node having value2 and next node of it     Node temp = start;     while (temp.data != value2)         temp = temp.next;     Node next = temp.next;       // insert new_node between temp and next.     temp.next = new_node;     new_node.prev = temp;     new_node.next = next;     next.prev = new_node; }   // this code is contributed by shivanisinghss2110

## Javascript



Following is a complete program that uses all of the above methods to create a circular doubly linked list.

## C++

 // C++ program to illustrate inserting a Node in // a Circular Doubly Linked list in begging, end // and middle #include using namespace std;   // Structure of a Node struct Node {     int data;     struct Node* next;     struct Node* prev; };   // Function to insert at the end void insertEnd(struct Node** start, int value) {     // If the list is empty, create a single node     // circular and doubly list     if (*start == NULL) {         struct Node* new_node = new Node;         new_node->data = value;         new_node->next = new_node->prev = new_node;         *start = new_node;         return;     }       // If list is not empty       /* Find last node */     Node* last = (*start)->prev;       // Create Node dynamically     struct Node* new_node = new Node;     new_node->data = value;       // Start is going to be next of new_node     new_node->next = *start;       // Make new node previous of start     (*start)->prev = new_node;       // Make last previous of new node     new_node->prev = last;       // Make new node next of old last     last->next = new_node; }   // Function to insert Node at the beginning // of the List, void insertBegin(struct Node** start, int value) {     // Pointer points to last Node     struct Node* last = (*start)->prev;       struct Node* new_node = new Node;     new_node->data = value; // Inserting the data       // setting up previous and next of new node     new_node->next = *start;     new_node->prev = last;       // Update next and previous pointers of start     // and last.     last->next = (*start)->prev = new_node;       // Update start pointer     *start = new_node; }   // Function to insert node with value as value1. // The new node is inserted after the node with // with value2 void insertAfter(struct Node** start, int value1,                  int value2) {     struct Node* new_node = new Node;     new_node->data = value1; // Inserting the data       // Find node having value2 and next node of it     struct Node* temp = *start;     while (temp->data != value2)         temp = temp->next;     struct Node* next = temp->next;       // insert new_node between temp and next.     temp->next = new_node;     new_node->prev = temp;     new_node->next = next;     next->prev = new_node; }   void display(struct Node* start) {     struct Node* temp = start;       printf("\nTraversal in forward direction \n");     while (temp->next != start) {         printf("%d ", temp->data);         temp = temp->next;     }     printf("%d ", temp->data);       printf("\nTraversal in reverse direction \n");     Node* last = start->prev;     temp = last;     while (temp->prev != last) {         printf("%d ", temp->data);         temp = temp->prev;     }     printf("%d ", temp->data); }   /* Driver program to test above functions*/ int main() {     /* Start with the empty list */     struct Node* start = NULL;       // Insert 5. So linked list becomes 5->NULL     insertEnd(&start, 5);       // Insert 4 at the beginning. So linked     // list becomes 4->5     insertBegin(&start, 4);       // Insert 7 at the end. So linked list     // becomes 4->5->7     insertEnd(&start, 7);       // Insert 8 at the end. So linked list     // becomes 4->5->7->8     insertEnd(&start, 8);       // Insert 6, after 5. So linked list     // becomes 4->5->6->7->8     insertAfter(&start, 6, 5);       printf("Created circular doubly linked list is: ");     display(start);       return 0; }

## Java

 // Java program to illustrate inserting a Node in // a Circular Doubly Linked list in begging, end // and middle import java.util.*;   class GFG {       static Node start;       // Structure of a Node     static class Node {         int data;         Node next;         Node prev;     };       // Function to insert at the end     static void insertEnd(int value)     {         // If the list is empty, create a single node         // circular and doubly list         if (start == null) {             Node new_node = new Node();             new_node.data = value;             new_node.next = new_node.prev = new_node;             start = new_node;             return;         }           // If list is not empty           /* Find last node */         Node last = (start).prev;           // Create Node dynamically         Node new_node = new Node();         new_node.data = value;           // Start is going to be next of new_node         new_node.next = start;           // Make new node previous of start         (start).prev = new_node;           // Make last previous of new node         new_node.prev = last;           // Make new node next of old last         last.next = new_node;     }       // Function to insert Node at the beginning     // of the List,     static void insertBegin(int value)     {         // Pointer points to last Node         Node last = (start).prev;           Node new_node = new Node();         new_node.data = value; // Inserting the data           // setting up previous and next of new node         new_node.next = start;         new_node.prev = last;           // Update next and previous pointers of start         // and last.         last.next = (start).prev = new_node;           // Update start pointer         start = new_node;     }       // Function to insert node with value as value1.     // The new node is inserted after the node with     // with value2     static void insertAfter(int value1, int value2)     {         Node new_node = new Node();         new_node.data = value1; // Inserting the data           // Find node having value2 and next node of it         Node temp = start;         while (temp.data != value2)             temp = temp.next;         Node next = temp.next;           // insert new_node between temp and next.         temp.next = new_node;         new_node.prev = temp;         new_node.next = next;         next.prev = new_node;     }       static void display()     {         Node temp = start;           System.out.printf(             "\nTraversal in forward direction \n");         while (temp.next != start) {             System.out.printf("%d ", temp.data);             temp = temp.next;         }         System.out.printf("%d ", temp.data);           System.out.printf(             "\nTraversal in reverse direction \n");         Node last = start.prev;         temp = last;         while (temp.prev != last) {             System.out.printf("%d ", temp.data);             temp = temp.prev;         }         System.out.printf("%d ", temp.data);     }       /* Driver code*/     public static void main(String[] args)     {         /* Start with the empty list */         Node start = null;           // Insert 5. So linked list becomes 5.null         insertEnd(5);           // Insert 4 at the beginning. So linked         // list becomes 4.5         insertBegin(4);           // Insert 7 at the end. So linked list         // becomes 4.5.7         insertEnd(7);           // Insert 8 at the end. So linked list         // becomes 4.5.7.8         insertEnd(8);           // Insert 6, after 5. So linked list         // becomes 4.5.6.7.8         insertAfter(6, 5);           System.out.printf(             "Created circular doubly linked list is: ");         display();     } }   // This code is contributed by Rajput-Ji

## Python3

 # Python3 program to illustrate inserting # a Node in a Circular Doubly Linked list # in begging, end and middle   # Structure of a Node class Node:     def __init__(self, data):         self.data = data         self.next = None         self.prev = None   # Function to insert at the end     def insertEnd(value):     global start       # If the list is empty, create a     # single node circular and doubly list     if (start == None):           new_node = Node(0)         new_node.data = value         new_node.next = new_node.prev = new_node         start = new_node         return       # If list is not empty       # Find last node */     last = (start).prev       # Create Node dynamically     new_node = Node(0)     new_node.data = value       # Start is going to be next of new_node     new_node.next = start       # Make new node previous of start     (start).prev = new_node       # Make last previous of new node     new_node.prev = last       # Make new node next of old last     last.next = new_node   # Function to insert Node at the beginning # of the List,     def insertBegin(value):     global start       # Pointer points to last Node     last = (start).prev       new_node = Node(0)     new_node.data = value  # Inserting the data       # setting up previous and     # next of new node     new_node.next = start     new_node.prev = last       # Update next and previous pointers     # of start and last.     last.next = (start).prev = new_node       # Update start pointer     start = new_node   # Function to insert node with value as value1. # The new node is inserted after the node with # with value2     def insertAfter(value1, value2):     global start     new_node = Node(0)     new_node.data = value1  # Inserting the data       # Find node having value2 and     # next node of it     temp = start     while (temp.data != value2):         temp = temp.next     next = temp.next       # insert new_node between temp and next.     temp.next = new_node     new_node.prev = temp     new_node.next = next     next.prev = new_node     def display():     global start     temp = start       print("Traversal in forward direction:")     while (temp.next != start):           print(temp.data, end=" ")         temp = temp.next       print(temp.data)       print("Traversal in reverse direction:")     last = start.prev     temp = last     while (temp.prev != last):           print(temp.data, end=" ")         temp = temp.prev       print(temp.data)     # Driver Code if __name__ == '__main__':     global start       # Start with the empty list     start = None       # Insert 5. So linked list becomes 5.None     insertEnd(5)       # Insert 4 at the beginning. So linked     # list becomes 4.5     insertBegin(4)       # Insert 7 at the end. So linked list     # becomes 4.5.7     insertEnd(7)       # Insert 8 at the end. So linked list     # becomes 4.5.7.8     insertEnd(8)       # Insert 6, after 5. So linked list     # becomes 4.5.6.7.8     insertAfter(6, 5)       print("Created circular doubly linked list is: ")     display()   # This code is contributed by Arnab kundu

## C#

 // C# program to illustrate inserting a Node in // a Circular Doubly Linked list in begging, end // and middle using System; using System.Collections.Generic;   class GFG {     static Node start;       // Structure of a Node     public class Node {         public int data;         public Node next;         public Node prev;     };       // Function to insert at the end     static void insertEnd(int value)     {         Node new_node;           // If the list is empty, create a single node         // circular and doubly list         if (start == null) {             new_node = new Node();             new_node.data = value;             new_node.next = new_node.prev = new_node;             start = new_node;             return;         }           // If list is not empty           /* Find last node */         Node last = (start).prev;           // Create Node dynamically         new_node = new Node();         new_node.data = value;           // Start is going to be next of new_node         new_node.next = start;           // Make new node previous of start         (start).prev = new_node;           // Make last previous of new node         new_node.prev = last;           // Make new node next of old last         last.next = new_node;     }       // Function to insert Node at the beginning     // of the List,     static void insertBegin(int value)     {         // Pointer points to last Node         Node last = (start).prev;           Node new_node = new Node();         new_node.data = value; // Inserting the data           // setting up previous and next of new node         new_node.next = start;         new_node.prev = last;           // Update next and previous pointers of start         // and last.         last.next = (start).prev = new_node;           // Update start pointer         start = new_node;     }       // Function to insert node with value as value1.     // The new node is inserted after the node with     // with value2     static void insertAfter(int value1, int value2)     {         Node new_node = new Node();         new_node.data = value1; // Inserting the data           // Find node having value2 and next node of it         Node temp = start;         while (temp.data != value2)             temp = temp.next;         Node next = temp.next;           // insert new_node between temp and next.         temp.next = new_node;         new_node.prev = temp;         new_node.next = next;         next.prev = new_node;     }       static void display()     {         Node temp = start;           Console.Write(             "\nTraversal in forward direction \n");         while (temp.next != start) {             Console.Write("{0} ", temp.data);             temp = temp.next;         }         Console.Write("{0} ", temp.data);           Console.Write(             "\nTraversal in reverse direction \n");         Node last = start.prev;         temp = last;         while (temp.prev != last) {             Console.Write("{0} ", temp.data);             temp = temp.prev;         }         Console.Write("{0} ", temp.data);     }       /* Driver code*/     public static void Main(String[] args)     {         /* Start with the empty list */         Node start = null;           // Insert 5. So linked list becomes 5.null         insertEnd(5);           // Insert 4 at the beginning. So linked         // list becomes 4.5         insertBegin(4);           // Insert 7 at the end. So linked list         // becomes 4.5.7         insertEnd(7);           // Insert 8 at the end. So linked list         // becomes 4.5.7.8         insertEnd(8);           // Insert 6, after 5. So linked list         // becomes 4.5.6.7.8         insertAfter(6, 5);           Console.Write(             "Created circular doubly linked list is: ");         display();     } }   // This code is contributed by Rajput-Ji

## Javascript

 // JavaScript program to illustrate inserting a Node in // a Circular Doubly Linked list in begging, end // and middle var start = null;   // Structure of a Node class Node {   constructor() {     this.data = 0;     this.next = null;     this.prev = null;   } }   // Function to insert at the end function insertEnd(value) {   var new_node;     // If the list is empty, create a single node   // circular and doubly list   if (start == null) {     new_node = new Node();     new_node.data = value;     new_node.next = new_node.prev = new_node;     start = new_node;     return;   }     // If list is not empty     /* Find last node */   var last = start.prev;     // Create Node dynamically   new_node = new Node();   new_node.data = value;     // Start is going to be next of new_node   new_node.next = start;     // Make new node previous of start   start.prev = new_node;     // Make last previous of new node   new_node.prev = last;     // Make new node next of old last   last.next = new_node; }   // Function to insert Node at the beginning // of the List, function insertBegin(value) {   // Pointer points to last Node   var last = start.prev;     var new_node = new Node();   new_node.data = value; // Inserting the data     // setting up previous and next of new node   new_node.next = start;   new_node.prev = last;     // Update next and previous pointers of start   // and last.   last.next = start.prev = new_node;     // Update start pointer   start = new_node; }   // Function to insert node with value as value1. // The new node is inserted after the node with // with value2 function insertAfter(value1, value2) {   var new_node = new Node();   new_node.data = value1; // Inserting the data     // Find node having value2 and next node of it   var temp = start;   while (temp.data != value2) temp = temp.next;   var next = temp.next;     // insert new_node between temp and next.   temp.next = new_node;   new_node.prev = temp;   new_node.next = next;   next.prev = new_node; }   function display() {   var temp = start;     document.write("
Traversal in forward direction
");   while (temp.next != start) {     document.write(temp.data + " ");     temp = temp.next;   }   document.write(temp.data);     document.write("
Traversal in reverse direction
");   var last = start.prev;   temp = last;   while (temp.prev != last) {     document.write(temp.data + " ");     temp = temp.prev;   }   document.write(temp.data); }   /* Driver code*/ /* Start with the empty list */ var start = null;   // Insert 5. So linked list becomes 5.null insertEnd(5);   // Insert 4 at the beginning. So linked // list becomes 4.5 insertBegin(4);   // Insert 7 at the end. So linked list // becomes 4.5.7 insertEnd(7);   // Insert 8 at the end. So linked list // becomes 4.5.7.8 insertEnd(8);   // Insert 6, after 5. So linked list // becomes 4.5.6.7.8 insertAfter(6, 5);   document.write("Created circular doubly linked list is: "); display();

Output

Created circular doubly linked list is:
Traversal in forward direction
4 5 6 7 8
Traversal in reverse direction
8 7 6 5 4

Time Complexity: O(N)
Auxiliary Space: O(1), As constant extra space is used.

• The list can be traversed from both directions i.e. from head to tail or from tail to head.
• Jumping from head to tail or from tail to head is done in constant time O(1).
• Circular Doubly Linked Lists are used for the implementation of advanced data structures like the Fibonacci Heap.

• It takes slightly extra memory in each node to accommodate the previous pointer.
• Lots of pointers are involved while implementing or doing operations on a list. So, pointers should be handled carefully otherwise data of the list may get lost.

## Applications of Circular doubly linked list:

• Managing song playlists in media player applications.
• Managing shopping carts in online shopping.