05_Queue.cpp

#include <iostream>
using namespace std;

class Node {
public:
    int data;
    Node* next;
    
    Node(int value) {
        data = value;
        next = nullptr;
    }
};

class Queue {
private:
    Node* front;
    Node* rear;

public:
    Queue() {
        front = nullptr;
        rear = nullptr;
    }

    void Enqueue(int value) {
        Node* newNode = new Node(value);
        if (rear == nullptr) {
            front = rear = newNode;
            return;
        }
        rear->next = newNode;
        rear = newNode;
    }

    void Dequeue() {
        if (front == nullptr) {
            cout << "Queue is empty" << endl;
            return;
        }
        Node* temp = front;
        front = front->next;

        if (front == nullptr) {
            rear = nullptr;
        }

        delete temp;
    }

    void Front() {
        if (front == nullptr) {
            cout << "Queue is empty" << endl;
        } else {
            cout << "Front element: " << front->data << endl;
        }
    }

    void Display() {
        if (front == nullptr) {
            cout << "Queue is empty" << endl;
            return;
        }

        Node* temp = front;
        while (temp != nullptr) {
            cout << temp->data << " ";
            temp = temp->next;
        }
        cout << endl;
    }
};

int main() {
    Queue queue;

    queue.Enqueue(1);
    queue.Enqueue(2);
    queue.Enqueue(3);
    queue.Display();

    queue.Dequeue();
    queue.Display();

    queue.Front();

    return 0;
}