Program to Implement Priority Queue in Data Structures (C plus plus)

In this tutorial, we will learn about the Program to Implement Priority Queue in Data Structures (C plus plus).

/*C++ Program to Implement Priority Queue*/

#include <iostream>
#include <cstdlib>

using namespace std;
 
/*Declaring the node*/

struct node
{
	int prior;
	int data;
	struct node *link;
};

class priority_queue
{
    private:
        node *front;
    public:
        priority_queue()
        {
            front = NULL;
        }
        

        void insertion(int item, int prior)
        {
            node *tmp, *q;
            tmp = new node;
            tmp->data = item;
            tmp->prior = prior;
            if (front == NULL || prior < front->prior)
            {
                tmp->link = front;
                front = tmp;
            }
            
            else
            {
                q = front;
                while (q->link != NULL && q->link->prior <= prior)
                    q=q->link;
                tmp->link = q->link;
                q->link = tmp;
            }
        }
        

        void deletion()
        {
            node *tmp;
            if(front == NULL)
                cout<<"Queue Underflowed "<<endl;
                
            else
            {
                tmp = front;
                cout<<"Deleted value is: "<<tmp->data<<endl;
                front = front->link;
                free(tmp);
            }
        }

        void show()
        {
            node *ptr;
            ptr = front;
            if (front == NULL)
                cout<<"Empty Queue "<<endl;
                
            else
            {	cout<<"Queue is: "<<endl;
                cout<<"Priority       Value "<<endl;
                while(ptr != NULL)
                {
                    cout<<ptr->prior<<"                 "<<ptr->data<<endl;
                    ptr = ptr->link;
                }
            }
        }
};

int main()
{
    int ch, val, prior;
    priority_queue pq; 
    do
    {
        cout<<"1. Insertion "<<endl;
        cout<<"2. Deletion "<<endl;
        cout<<"3. Display "<<endl;
        cout<<"4. Exit "<<endl;
        cout<<"Please enter your choice : "; 
        cin>>ch;
        
        switch(ch)
        {
        case 1:
            cout<<"Please enter the value to be added in the queue : ";
            cin>>val;
            cout<<"Please enter its priority : ";
            cin>>prior;
            pq.insertion(val, prior);
            break;
        case 2:
            pq.deletion();
            break;
        case 3:
            pq.show();
            break;
        case 4:
            break;
        default :
            cout<<"Invalid entry"<<endl;
        }
    }
    while(ch != 4);
    return 0;
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

/*C++ Program to Implement Priority Queue*/

#include <iostream>

#include <cstdlib>

using namespace std;

/*Declaring the node*/

struct node

{

int prior;

int data;

struct node *link;

};

class priority_queue

{

private:

node *front;

public:

priority_queue()

{

front = NULL;

}

void insertion(int item, int prior)

{

node *tmp, *q;

tmp = new node;

tmp->data = item;

tmp->prior = prior;

if (front == NULL || prior < front->prior)

{

tmp->link = front;

front = tmp;

}

else

{

q = front;

while

(q->link != NULL && q->link->prior <= prior)

q=q->link;

tmp->link = q->link;

q->link = tmp;

}

void deletion()

{

node *tmp;

if(front == NULL)

cout<<"Queue Underflowed "<<endl;

else

{

tmp = front;

cout<<"Deleted value is: "<<tmp->data<<endl;

front = front->link;

free(

tmp);

}

void show()

{

node *ptr;

ptr = front;

if (front == NULL)

cout<<"Empty Queue "<<endl;

else

{ cout<<"Queue is: "<<endl;

cout<<"Priority Value "<<endl;

while(ptr != NULL)

{

cout<<ptr->prior<<" "<<ptr->data<<endl;

ptr = ptr->link;

}

};

int main()

{

int ch, val, prior;

priority_queue pq;

{

cout<<"1. Insertion "<<endl;

cout<<"2. Deletion "<<endl;

cout<<"3. Display "<<endl;

cout<<"4. Exit "<<endl;

cout<<"Please enter your choice : ";

cin>>ch;

switch(ch)

{

case 1:

cout<<"Please enter the value to be added in the queue : ";

cin>>val;

cout<<"Please enter its priority : ";

cin>>prior;

pq.insertion(val, prior);

break;

case 2:

pq.deletion();

break;

case 3:

pq.show();

break;

case 4:

break;

default :

cout<<"Invalid entry"<<endl;

}

while(ch != 4);

return 0;

}

Output:

Program to Implement Priority Queue in Data Structures (C plus plus)