Java Programs - Solved 2013 Theory Paper ISC Computer Science

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Solved 2013 Theory Paper ISC Computer Science

Class 12 - ISC Computer Science Solved Theory Papers

Dequeue Queue Program - ISC 2013 Theory

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:

Class name: Dequeue
Data members/instance variables:
arr[ ]: array to hold up to 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.

Member functions:
Dequeue(int l): constructor to initialize 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 deletion is possible from the front end, otherwise returns -9999.
int popRear(): returns element from rear if deletion is possible from the rear end, otherwise returns -9999.

Specify the class Dequeue giving details of the constructor, void addFront(int), void addRear(int), int popFront() and int popRear().

The main function and algorithm need not be written.

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

    public void addFront(int val){
        if(front - 1 >= 0)
            arr[--front] = val;
        else
            System.out.println("Overflow from front");
    }

    public void addRear(int val){
        if(rear + 1 < lim)
            arr[++rear] = val;
        else
            System.out.println("Overflow from rear");
    }

    public int popFront(){
        if(front + 1 <= rear) 
            return arr[front--]; 
        return -9999; } 
    public int popRear(){ 
        if(rear - 1 >= front)
            return arr[rear--];
        return -9999;
    }
}                            

 
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