Doubly Circular Linked List | Set 1 (Introduction and Insertion)
Prerequisite: Doubly Linked list, Circular Linked List
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 previous and next pointer and the last node points to first node by next pointer and also the first node points to last node by previous pointer.
Following is representation of a Circular doubly linked list node in C/C++:
// Structure of the node
struct node
{
int data;
struct node *next; // Pointer to next node
struct node *prev; // Pointer to previous node
};
Insertion in Circular Doubly Linked List
Insertion in Circular Doubly Linked List
- Insertion at the end of list or in an empty list
- Empty List (start = NULL): A node(Say N) is inserted with data = 5, so previous pointer of N points to N and next pointer of N also points to N. But now start pointer points to the first node the list.
- Empty List (start = NULL): A node(Say N) is inserted with data = 5, so previous pointer of N points to N and next pointer of N also points to N. But now start pointer points to the first node the list.
- List initially contain some nodes, start points to first node of the List: A node(Say M) is inserted with data = 7, so previous pointer of M points to last node, next pointer of M points to first node and last node’s next pointer points to this M node and first node’s previous pointer points to this M node.
C++
// Function to insert at the endvoid 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 preivous of new node new_node->prev = last; // Make new node next of old last last->next = new_node;} |
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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 preivous 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 |
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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 preivous of new node new_node.prev = last; // Make new node next of old last last.next = new_node; } // This code is contrbuted by Pratham76 |
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- 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 first node of the list, T previous pointer points to last node 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.
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;} |
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- 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.
C++
// Function to insert node with value as value1.// The new node is inserted after the node with// with value2void 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;} |
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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 Cicular Doubly Linked list in begging, end// and middle#include <bits/stdc++.h>using namespace std;// Structure of a Nodestruct Node{ int data; struct Node *next; struct Node *prev;};// Function to insert at the endvoid 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 preivous 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 value2void 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;} |
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Java
// Java program to illustrate inserting a Node in // a Cicular 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 preivous 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 |
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Python3
# Python3 program to illustrate inserting # a Node in a Cicular Doubly Linked list # in begging, end and middle start = None# 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 preivous 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 |
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C#
// C# program to illustrate inserting a Node in // a Cicular 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 preivous 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 |
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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
Following are advantages and disadvantages of circular doubly linked list:
Advantages:
- List can be traversed from both the 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 implementation of advanced data structures like Fibonacci Heap.
Disadvantages
- It takes slightly extra memory in each node to accommodate previous pointer.
- Lots of pointers 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 songs playlist in media player applications.
- Managing shopping cart in online shopping.
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