![]() The code to push a value to the Stack or enqueue a value to the queue should be amended to only push or enqueue the value if the stack or the queue have not reached their maximum capacity. This property should be initialised based on a parameter passed using the constructor of each class. Update the above Stack Class and Queue Class to have an extra private property called maxCapacity (positive integer value). ![]() It also enables us to create and name our own methods, pop(), push(), enqueue() and dequeue() to match the terminology used when using stacks or queues. Using Object Oriented Programming (OOP) enables us to prevent direct access to the list (defined as a private attribute – This is an example of encapsulation a key concept in OOP). In the following trinket we are creating our own classes, Queue and Stack. When you add ( push) a book on top of the pile, it will be the first book that you will then take ( pop) from the pile (stack).īoth stacks and queues can easily be implemented in Python using a list and the append(), pop() and remove() functions. Imagine a stack of books piled up on a table. ![]() An item that is added ( enqueue) at the end of a queue will be the last one to be accessed ( dequeue).Ī stack is a FILO data structure: First-In Last-Out. and Queues are two key data structures often used in programming.Ī queue is a FIFO data structure: First-In First-Out in other words, it is used to implement a first come first served approach. Fails to enqueue because front = 0 & rear = SIZE - 1 * Function to display status of Circular Queue */įor (i = front i != rear i = (i + 1) % SIZE) } /* Q has only one element, so we reset the queue after deleting it. Print("After removing an element from the queue") # Your M圜ircularQueue object will be instantiated and called as such: Print("No element in the circular queue")įor i in range(self.head, self.tail + 1): # Delete an element from the circular queue If ((self.tail + 1) % self.k = self.head): # Insert an element into the circular queue # Circular Queue implementation in Python for the last element, reset the values of FRONT and REAR to -1.circularly increase the FRONT index by 1.add the new element in the position pointed to by REAR.if the rear reaches the end, next it would be at the start of the queue) circularly increase the REAR index by 1 (i.e.for the first element, set value of FRONT to 0.initially, set value of FRONT and REAR to -1.REAR track the last elements of the queue.FRONT track the first element of the queue.If REAR + 1 = 5 (overflow!), REAR = (REAR + 1)%5 = 0 (start of queue) Here, the circular increment is performed by modulo division with the queue size. when we try to increment the pointer and we reach the end of the queue, we start from the beginning of the queue. This reduces the actual size of the queue.Ĭircular Queue works by the process of circular increment i.e. Note: In case of linked list implementation, a queue can be easily implemented without being circular. Auxiliary Space: O(n) where n is the maximum number of elements that can be stored in the queue. Here, indexes 0 and 1 can only be used after resetting the queue (deletion of all elements). Time Complexity: Time complexity of enQueue(), deQueue() operation is O(1) as there is no loop in any of the operation. In a normal queue, after a bit of insertion and deletion, there will be non-usable empty space. The circular queue solves the major limitation of the normal queue. Decrease Key and Delete Node Operations on a Fibonacci HeapĪ circular queue is the extended version of a regular queue where the last element is connected to the first element.
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