earthanna.blogg.se - Enqueue python

ENQUEUE PYTHON HOW TO

The following steps can be seen as a flow chart to the operation of the Circular Queue: This means that the position 0 will always contain an element which is not how an actual queue/circular queue works. This is because once an element is removed, the list automatically shifts all the other elements by one position to the left. Note: During a dequeue operation, the Head pointer will be incremented by 1 but no element will actually be removed from the queue.

To do this, we need to treat Lists like arrays, hence we will restrict its size.

ENQUEUE PYTHON HOW TO

Let's see how to implement it using the language agnostic method. I hope you now feel confident that you know what a circular queue is. For instance, Head = 14, Tail = 5 and Size of Queue = 15, then the number of elements = 15 - (14 - 5) = 6

Head>Tail: Number of elements = (Size of Queue) - (Head-Tail) = (Size of Queue) - Head + Tail.

For instance, if Head = 2 and Tail = 5, then the number of elements will be 5 - 2 = 3

Tail>=Head: Number of elements = Tail - Head.

It is for this reason that it is called a circular queue. Here you will observe that the elements are inserted from the 14th position and then it restarts from 0. You should also try doing three or four dequeue operations and then enqueueing an element. The queue is considered full, even though there is one empty spot left. This is because the Tail has no empty spot to point to after an element is inserted in the 14th position. In the above animation, if you tried to fill the queue completely you wouldn't be able to enqueue after the 13th position.

Tail pointer - Points to the next empty spot in which the new element can be inserted.

Or in other words, it points to the element to be removed if the dequeue operation is called.

Head pointer - Points to the front of the Queue.Observations based on the above animation: This is possible because the Head and Tail pointers are allowed to cross each other.Ĭheck out this animation to understand the circular queue a bit better. The Head can be greater than the Tail or vice-versa.The Tail and Head can point to the same location - this means the Queue is empty.This means that once the Head or Tail reaches the end of the Queue, it resets itself to 0. There is no need to reset Head and Tail pointers since they reset themselves.A Circular Queue can be seen as an improvement over the Linear Queue because: Circular Queues are widely used and are often tested on job interviews. Basic Python data structure concepts - listsīefore you go ahead and read this tutorial, I highly recommend you to read our previous tutorial on Queues as we will be building off of those concepts.Linear Queues (you can learn more here).To learn about Circular Queue, you should first have a good understanding of the following:

Last Updated: Wednesday 29 th December 2021 Prerequisites