Question

A doubly queue is a linear data structure which enables the user to add and remove integers from either ends , i.e from front or rear. Define a class Dequeue with the following details:
Classname:Dequeue
Data members / instance variables:

arr[]:array to hold upto 100 integer elements
lim: stores the limit of the dequeue
front:to point to the index of front end
rear:to point to the index of rear end
Memberfunctions:

Dequeue(int l):constructor to initialize the data members lim=l,front=rear=0

void addfront(int val):to add integer from the front if possible else display the message(“Overflow from front”)
void addrear(int val):to add integer from the rear if possible else display the message(“Overflow from rear”)
int popfront():returns element from front, if possible otherwise returns -9999
int poprear():returns element from rear, if possible otherwise returns -9999

Specify the class Dequeue giving details of the constructor(int), void addfront(int) , void addrear(int) , int popfront() and int poprear().
The main function and algorithm need not be written.

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Code

				
					public class Dequeue
{
    int arr[]=new int[100];
    int lim,front,rear;
    Dequeue(int l)
    {
        lim=l;
        front=0;
        rear=0;
        arr=new int[lim];
     
    }



    void addrear(int val)
    {
        if(rear< lim)
        {

            arr[rear++]=val;
        }
        else
        {
            System.out.println("OVERFLOW");
        }

    }
    int poprear()
    {
        
        //if front and rear are at zero which means nothing is entered
        if(front==0&&rear==0 )  
        {
            
            return -9999;
        }
        
        else 
        {
            rear=rear-1;
            return arr[rear];
        }
       
    }

    int popfront()
    {

        //If front is equal to rear that means that either  all elements of array are deleted
        // or no elements are added
        if(front==rear)
        {
            front=0;
            rear=0;
            return -9999;
        }

        else
        {

            return arr[front++];
        }
        
    }

    void addfront(int val)
    {
        if(front>0)
        {
            front=front-1;
            arr[front]=val;

        }
        else
        {
            System.out.println("Overflow from front");
        }
    }
    void display()
    {
     for (int i=front;i< rear;i++)
     {
         System.out.println(arr[i]);
        }
    }
}