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Update doubly_linked_list.py (#545)

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Aditya Sharma 2018-10-31 13:04:55 +05:30 committed by Harshil
parent 6db1994de2
commit 1b19028117
1 changed files with 22 additions and 21 deletions
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data_structures/linked_list/doubly_linked_list.py
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@ -2,11 +2,12 @@
- A linked list is similar to an array, it holds values. However, links in a linked list do not have indexes. - A linked list is similar to an array, it holds values. However, links in a linked list do not have indexes.
- This is an example of a double ended, doubly linked list. - This is an example of a double ended, doubly linked list.
- Each link references the next link and the previous one. - Each link references the next link and the previous one.
''' - A Doubly Linked List (DLL) contains an extra pointer, typically called previous pointer, together with next pointer and data which are there in singly linked list.
- Advantages over SLL - IT can be traversed in both forward and backward direction.,Delete operation is more efficent'''
from __future__ import print_function from __future__ import print_function
class LinkedList: class LinkedList: #making main class named linked list
def __init__(self): def __init__(self):
self.head = None self.head = None
self.tail = None self.tail = None
@ -25,7 +26,7 @@ class LinkedList:
self.head = self.head.next # oldHead <--> 2ndElement(head) self.head = self.head.next # oldHead <--> 2ndElement(head)
self.head.previous = None # oldHead --> 2ndElement(head) nothing pointing at it so the old head will be removed self.head.previous = None # oldHead --> 2ndElement(head) nothing pointing at it so the old head will be removed
if(self.head is None): if(self.head is None):
self.tail = None self.tail = None #if empty linked list
return temp return temp
def insertTail(self, x): def insertTail(self, x):