Untitled

#include <iostream>
using namespace std;

class Node {
public:
    int data;
    Node* prev;
    Node* next;
};

class DoublyLinkedList {
public:
    Node* head;
    Node* tail;

    DoublyLinkedList() {
        head = nullptr;
        tail = nullptr;
    }

    void push(int data) {
        Node* newNode = new Node;
        newNode->data = data;
        newNode->prev = nullptr;
        newNode->next = head;
        if (head != nullptr) {
            head->prev = newNode;
        }
        else {
            tail = newNode;
        }
        head = newNode;
    }

    void pop() {
        if (head == nullptr) {
            return;
        }
        Node* temp = head;
        head = head->next;
        if (head != nullptr) {
            head->prev = nullptr;
        }
        else {
            tail = nullptr;
        }
        delete temp;
    }

    bool update(int oldData, int newData) {
        Node* current = head;
        while (current != nullptr) {
            if (current->data == oldData) {
                current->data = newData;
                return true;
            }
            current = current->next;
        }
        return false;
    }

    void deleteAll() {
        Node* current = head;
        while (current != nullptr) {
            Node* temp = current;
            current = current->next;
            delete temp;
        }
        head = nullptr;
        tail = nullptr;
    }

    void display() {
        Node* current = head;
        while (current != nullptr) {
            cout << current->data << " ";
            current = current->next;
        }
        cout << endl;
    }
};

int main() {
    DoublyLinkedList list;
    while (true) {
        cout << "1. Add data" << endl;
        cout << "2. Delete data" << endl;
        cout << "3. Update data" << endl;
        cout << "4. Clear data" << endl;
        cout << "5. Display data" << endl;
        cout << "6. Exit" << endl;
        int choice;
        cout << "Enter your choice: ";
        cin >> choice;
        switch (choice) {
        case 1: {
            int data;
            cout << "Enter data to add: ";
            cin >> data;
            list.push(data);
            break;
        }
        case 2: {
            list.pop();
            break;
        }
        case 3: {
            int oldData, newData;
            cout << "Enter old data: ";
            cin >> oldData;
            cout << "Enter new data: ";
            cin >> newData;
            bool updated = list.update(oldData, newData);
            if (!updated) {
                cout << "Data not found" << endl;
            }
            break;
        }
        case 4: {
            list.deleteAll();
            break;
        }
        case 5: {
            list.display();
            break;
        }
        case 6: {
            return 0;
        }
        default: {
            cout << "Invalid choice" << endl;
            break;
        }
        }
    }
    return 0;
}