Circular Queue and Doubly Ended Queue

[Avishake007]

I want to add circular queue and doubly ended queue part in queue.py file. Please assign me for this project. I am a GSSOC'21 participant and wants to contribute for this project.

[Simar05519]

I want to work on this issue. Please assign to me

[Smit-create]

We don't assign issues. Whoever wants to work on it are free to do so. But before opening the PR do discuss the API and implementation plan. And to my notice, double_ended is already present

[ANAMIKA1410]

// C++ implementation of De-queue using circular // array

include

using namespace std;

// Maximum size of array or Dequeue

define MAX 100

// A structure to represent a Deque class Deque { int arr[MAX]; int front; int rear; int size; public : Deque(int size) { front = -1; rear = 0; this->size = size; }

// Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool isEmpty();
int getFront();
int getRear();

};

// Checks whether Deque is full or not. bool Deque::isFull() { return ((front == 0 && rear == size-1)|| front == rear+1); }

// Checks whether Deque is empty or not. bool Deque::isEmpty () { return (front == -1); }

// Inserts an element at front void Deque::insertfront(int key) { // check whether Deque if full or not if (isFull()) { cout << "Overflow\n" << endl; return; }

// If queue is initially empty
if (front == -1)
{
    front = 0;
    rear = 0;
}

// front is at first position of queue
else if (front == 0)
    front = size - 1 ;

else // decrement front end by '1'
    front = front-1;

// insert current element into Deque
arr[front] = key ;

}

// function to inset element at rear end // of Deque. void Deque ::insertrear(int key) { if (isFull()) { cout << " Overflow\n " << endl; return; }

// If queue is initially empty
if (front == -1)
{
    front = 0;
    rear = 0;
}

// rear is at last position of queue
else if (rear == size-1)
    rear = 0;

// increment rear end by '1'
else
    rear = rear+1;

// insert current element into Deque
arr[rear] = key ;

}

// Deletes element at front end of Deque void Deque ::deletefront() { // check whether Deque is empty or not if (isEmpty()) { cout << "Queue Underflow\n" << endl; return ; }

// Deque has only one element
if (front == rear)
{
    front = -1;
    rear = -1;
}
else
    // back to initial position
    if (front == size -1)
        front = 0;

    else // increment front by '1' to remove current
        // front value from Deque
        front = front+1;

}

// Delete element at rear end of Deque void Deque::deleterear() { if (isEmpty()) { cout << " Underflow\n" << endl ; return ; }

// Deque has only one element
if (front == rear)
{
    front = -1;
    rear = -1;
}
else if (rear == 0)
    rear = size-1;
else
    rear = rear-1;

}

// Returns front element of Deque int Deque::getFront() { // check whether Deque is empty or not if (isEmpty()) { cout << " Underflow\n" << endl; return -1 ; } return arr[front]; }

// function return rear element of Deque int Deque::getRear() { // check whether Deque is empty or not if(isEmpty() || rear < 0) { cout << " Underflow\n" << endl; return -1 ; } return arr[rear]; }

// Driver program to test above function int main() { Deque dq(5); cout << "Insert element at rear end : 5 \n"; dq.insertrear(5);

cout << "insert element at rear end : 10 \n";
dq.insertrear(10);

cout << "get rear element " << " "
    << dq.getRear() << endl;

dq.deleterear();
cout << "After delete rear element new rear"
    << " become " << dq.getRear() << endl;

cout << "inserting element at front end \n";
dq.insertfront(15);

cout << "get front element " << " "
    << dq.getFront() << endl;

dq.deletefront();

cout << "After delete front element new "
<< "front become " << dq.getFront() << endl;
return 0;

}