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Queue Data Structure

Aya Bouchiha
Full stack web developer
Updated on ・1 min read

Hi, today, we're going to discuss queue :)

Definition Of Queue

A Queue is a linear data structure that stores items in a First-In/First-Out (FIFO) manner. In Queue, the element that goes in first is the element that comes out first.

queue data structure

Space and Time complexity

the space complexity of a queue is O(n)

add ( enqueue ) remove (dequeue) search access
O(1) O(1) O(n) O(n)

Implementation of queue using python

class Queue:

    def __init__(self,size):
        self.items = []
        self.front = self.rear = 0 
        self.size = size
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Enqueue

def enqueue(self,data):
        if not self.isFull()  :
            self.items.append(data)
            self.rear += 1 
            return f'{self.items[-1]} added'
        else:
            return 'full'
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Dequeue

def dequeue(self):
        if not self.isEmpty() :
            self.items.pop(0)
            self.rear -= 1 
            return 'deleted successfuly'
        return 'empty'
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isEmpty

    def isEmpty(self) -> bool:
        return  self.rear == self.front
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isFull

    def isFull(self) -> bool :
        return self.size == self.rear
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References and useful ressources

#day_3
Have a good day!

Discussion (2)

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matijs6 profile image
Matijs

Hello everyone. This is my first comment on this platform.

Could you provide some examples were this structure would be useful?

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ayabouchiha profile image
Aya Bouchiha Author

Hi, this is a good quesion, we can use Queue in all kinds of customer service such as Call Center phone systems in banks or in big companies to hold people calling them in an order, until a service representative is free, in addition, It is used In operating systems, for controlling access to shared system resources like files, printers and disks,queue is used in routers or switches as well, however, it is used in many algorithmes like Round Robin Schedule, Breadth First Search .
Have a great day.