LinkedListImplementation.py

# Python3 program to demonstrate linked list
# based implementation of queue
 
# A linked list (LL) node
# to store a queue entry
class Node:     
    def __init__(self, data):
        self.data = data
        self.next = None
 
# A class to represent a queue
 
# The queue, front stores the front node
# of LL and rear stores ths last node of LL
class Queue:     
    def __init__(self):
        self.front = self.rear = None
 
    def isEmpty(self):
        return self.front is None
     
    # Method to add an item to the queue
    def EnQueue(self, item):
        temp = Node(item)         
        if self.rear is None:
            self.front = self.rear = temp
            return
        self.rear.next = temp
        self.rear = temp
 
    # Method to remove an item from queue
    def DeQueue(self):         
        if self.isEmpty():
            return
        temp = self.front
        self.front = temp.next 
        if(self.front is None):
            self.rear = None
        return str(temp.data)
 
# Driver Code
if __name__== '__main__':
    q = Queue()
    q.EnQueue(10)
    q.EnQueue(20)
    q.DeQueue()
    q.DeQueue()
    q.EnQueue(30)
    q.EnQueue(40)
    q.EnQueue(50)     
    print("Dequeued item is " + q.DeQueue())