56_PriorityQueue_LinkedList.cpp

#include <iostream>
using namespace std;

class Node
{
public:
    int data;
    int priority;
    Node *next = NULL;
    Node(int data, int priority)
    {
        this->data = data;
        this->priority = priority;
        this->next = NULL;
    }
};

class Queue
{
    Node *front;

public:
    Queue(int data, int priority)
    {
        Node *newnode = new Node(data, priority);
        front = newnode;
    }
    Queue()
    {
        front = NULL;
    }
    void insert(int data, int priority)
    {
        Node *newnode = new Node(data, priority);
        if (front == NULL || priority < front->priority)
        {
            newnode->next = front;
            front = newnode;
            return;
        }
        Node *temp = front;
        while (temp->next != NULL && temp->next->priority <= priority)
        {
            temp = temp->next;
        }
        newnode->next = temp->next;
        temp->next = newnode;
    }
    void del()
    {
        if (front == NULL)
        {
            cout << "Queue Underflow" << endl;
            return;
        }
        Node *temp = front;
        front = front->next;
        delete temp;
    }
    void Display()
    {
        if (front == NULL){
            cout << "Queue is empty"<<endl;
            return;
        }
        Node *temp = front;
            cout << "Queue is :"<<endl;
            cout << "Priority , Item\n";
            while (temp!= NULL)
            {
                cout << temp->priority << " , " << temp->data << endl;
                temp = temp->next;
            }
    }
};

int main()
{
    Queue q1(10, 1);
    q1.Display();
    q1.insert(15, 3);
    q1.insert(20, 2);
    q1.insert(30, 4);
    q1.Display();
    q1.del();
    q1.Display();
    q1.del();
    q1.Display();
    return 0;
}