Lecture 206:- Inserting in a Circular Linked List

To insert an element into a Circular Linked List, you need to consider three scenarios:

1. Insert at the beginning (head) of the Circular Linked List.
2. Insert at the end of the Circular Linked List.
3. Insert at a specific position in the Circular Linked List.

Here's a C++ implementation for inserting elements into a Circular Linked List:

cppCopy code

#include <iostream> class Node { public:    int data;    Node* next;    Node(int data) : data(data), next(nullptr) {} }; class CircularLinkedList { private:    Node* head; public:    CircularLinkedList() : head(nullptr) {}    ~CircularLinkedList() {        if (head) {            Node* current = head;            do {                Node* temp = current;                current = current->next;                delete temp;            } while (current != head);        }    }    void insertAtBeginning(int data) {        Node* newNode = new Node(data);        if (!head) {            head = newNode;            head->next = head; // Make the only node point to itself        } else {            newNode->next = head->next;            head->next = newNode;        }    }    void insertAtEnd(int data) {        Node* newNode = new Node(data);        if (!head) {            head = newNode;            head->next = head; // Make the only node point to itself        } else {            Node* current = head;            while (current->next != head) {                current = current->next;            }            current->next = newNode;            newNode->next = head; // Make the new node point back to the head        }    }    void insertAtPosition(int data, int position) {        if (position <= 0) {            insertAtBeginning(data);        } else {            Node* newNode = new Node(data);            Node* current = head;            int count = 0;            while (count < position - 1 && current->next != head) {                current = current->next;                count++;            }            newNode->next = current->next;            current->next = newNode;        }    }    void display() {        if (!head) {            std::cout << "List is empty." << std::endl;            return;        }        Node* current = head;        do {            std::cout << current->data << " -> ";            current = current->next;        } while (current != head);        std::cout << "Head" << std::endl;    } }; int main() {    CircularLinkedList list;    list.insertAtEnd(1);    list.insertAtEnd(3);    list.insertAtBeginning(0);    list.insertAtPosition(2, 2);    list.display(); // Output: 0 -> 1 -> 2 -> 3 -> Head    return 0; }

In this implementation, we've added three new methods to the CircularLinkedList class:

1. insertAtBeginning: Inserts a new node at the beginning (head) of the Circular Linked List. If the list is empty, the new node becomes the head and points to itself. Otherwise, the new node is inserted after the head node.
2. insertAtEnd: Inserts a new node at the end of the Circular Linked List. If the list is empty, the new node becomes the head and points to itself. Otherwise, we traverse to the last node and make it point to the new node, and the new node points back to the head.
3. insertAtPosition: Inserts a new node at a specific position in the Circular Linked List. If the position is less than or equal to 0, the node is inserted at the beginning. Otherwise, we traverse to the node before the desired position and insert the new node after it.

In the main function, we demonstrate how to use these insertion methods to create a Circular Linked List with elements 0, 1, 2, and 3, and then display the Circular Linked List.