Doubly Linked List | Program | Traversing Operation | Data Structures

In this Python Programming video tutorial you will learn about doubly Linked List data structure and also you will write the program for traversing operation in detail.

Data structure is a way of storing and organising the data so that it can be accessed effectively.
Linked List is a linear data structure made up of chain of nodes in which each node contains a data field and link or reference.

There are different types of linked list. Here we will discuss about 3 common types of linked list. doubly linked list is one of them. Here we will discuss doubly linked list operations and definitions in detail.

Here we will write two methods for traversing operation, one is for forward traversing and another for backward traversing.

Forward Traversing:
def print_LL(self):
print("Linked List is empty!")
else:
while n is not None:

Backward Traversing:
def print_LL_reverse(self):
print()
print("Linked List is empty!")
else:
while n is not None:


#DataStructures #PythonPrograms #LinkedList

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[SujithSujith-zlho]

wow its really good mam, i watch lot of data structure videos, those videos are really tough to understand but your videos are good, i quickly understand the data structure and the explanation, examples are good to under stand, thank you

[arnavverma]

14:00 Why didn't we use,
while n.pref is not None: ??
instead of, while n is not None:

[nayankamthe]

Best lecture, best technique, keep it up :).

[deepakmehra]

why don't you take self.tail as a parameter, it will easy to print backwards having self.tail

[factsworldtamil]

mam, you very clearly teach the concepts of linked list so that thank you mam , so could you upload a video for singly and doubly circular linked list mam.

[t.gowthamarasu]

Music player is one of the best example for linked list right?

[sahilsahane]

You have made many playlist wich one learn first

[rohankhatua]

Mam we can create a another instance variable in doublelinked list class. And travel easily in reverse order. In that case we need not to travel to last node to find it. Right mam?

[shaikafridi]

Can u please Start Circular Linked List after it? Please!!

[priyankakadam]

ma'am when I'm going to execute it's coming name "dll" not found

[rebelsk]

I'm not getting the o/p as you got !!!!
please suggest

[nguyenhuyhoangkhcm]

Can you elaborate on the meaning of nref and pref, please?

[anusree]

Mam how can we write this code as menu driven in python

[jaypeepcanlas]

How can I generate ramdom doubly linked list
please help me

[chaitanyamutyala]

In reverse transversal first node is not printing

[Badboy-dxti]

Mam expalin difference between while n is not none and while n.nref is not none

[manishbolbanda]

when to use while n.ref is not None and when to use while n is not None ??

[FindMultiBagger]

Can you make reverse operation in single list

[rebelsk]

class Node:
def _init_(self, data):
self.data = data
self.nref = None
self.pref = None

class doublyLL:
def _init_(self):
self.data = None

def print_LL(self):
if self.head is None:
print ("Linked list is empty")
else:
n=self.head
while n!= None:
print(n.data, "-->", end=" ")
n = n.nref

def print_LL_reverse(self):
if self.head is None:
print ("Linked list is empty")
else:
n=self.head
while n.nref is not None:
n = n.nref
dl1=doublyLL()
dl1.print_LL()


ERROR : -Traceback (most recent call last):
File "<string>", line 28, in <module>
File "<string>", line 12, in print_LL
AttributeError: 'doublyLL' object has no attribute 'head'
>

[gandeswaraj]

class Node:
def __init__(self, data):
self.data = None
self.nref = None
self.pref = None
class doubly_LL:
def __init__(self):
self.head = None

def print_LL(self):
if self.head is None:
print("Linked List is Empty")
else:
n = self.head
while n is not None:
print(n.data, "--", end = " ")
n = n.nref

def reverse_print_LL(self):
if self.head is None:
print("Linked List is Empty")
else:
n = self.head
while n.nref is not None:
n = n.nref
while n is not None:
print(n.data, "--", end = " ")
n = n.pref

def linked_list_empty(self, data):
if self.head is None:
new_node = Node(data)
self.head = new_node
else:
print("Linked List is Not Empty")

def add_begin(self, data):
new_node = Node(data)
if self.head is None:
self.head = Node(data)

else:
new_node.nref = self.head
self.head.pref = new_node
self.head = new_node









obj = doubly_LL()
obj.linked_list_empty(10)
obj.add_begin(20)
obj.print_LL()
obj.reverse_print_LL()




I am getting output as None None .
Any one can help me ?