This document introduces linked lists as an alternative data structure to arrays that allows for dynamic sizes and easier insertion/deletion of items. It describes how linked lists consist of nodes that point to the next node, including singly linked lists where each node points only to the next node. The key operations on singly linked lists are then discussed, including creating a list by adding nodes to the front or end, and deleting nodes from the front, interior, or end of the list.

1. Introduction to Linked List, creation of Singly
Linked List
21

2. • What are the limitations of an array, as a data structure?
– Fixed size
– Physically stored in consecutive memory locations
– To insert or delete items, may need to shift data
• Linked list provides two advantages over arrays
- Dynamic size
- Ease of insertion/deletion
Limitations of arrays

3. • A linked data structure consists of items that are linked to other items
– How? each item points to another item
• Singly linked list: each item points to the next item
• Doubly linked list: each item points to the next item and to the previous item
• Circular linked list: a singly linked list where the last item holds the address of the first item
Linked data structures

5. • A linked list is an ordered sequence of items called nodes
– A node is the basic unit of representation in a linked list
• A node in a singly linked list consists of two fields:
– A data portion
– A link (pointer) to the next node in the structure
• The first item (node) in the linked list is accessed via a front or head pointer
– The linked list is defined by its head (this is its starting point)
data link
Node

6. •Creating a list
•Traversing the list
•Inserting an item in the list
•Deleting an item from the list
•Concatenating two lists into one
Basic operations on a single linked list

7. # Node class
class Node:
def __init__(self, data):
self.data = data # Assign data
self.next = None # Initialize next as null
# Linked List class
class LinkedList:
def __init__(self):
self.start = None
data None
None
data next
self.start
newnode
Creation of a node

8. def createlist(self):
n=int(input("enter number of node")) #say n=3
for i in range(n):
data=int(input("enter value"))
newnode=Node(data)
if self.start==None:
self.start=newnode
else:
temp=self.start
while temp.next!=None:
temp=temp.next
temp.next=newnode
Single linked list – Algorithm

9. None
self.start
2000
self.start
21 None
2000
newnode
CASE 1: creation of first node
if self.start==None:
self.start=newnode
else:
temp=self.start
while temp.next!=None:
temp=temp.next
temp.next=newnode
Single linked list creation

10. 21 3000 22 None
2000 3000
2000
self.start
21 3000 22 4000
2000 3000
2000
self.start
23 None
4000
CASE 2: insertion of a node at tail
temp
temp newnode

11. We will now examine linked list operations:
• Add an item to the linked list
– We have 3 situations to consider:
• insert a node at the front
• insert a node after a given node.
• insert a node at the end
• Delete an item from the linked list
– We have 3 situations to consider:
• delete the node at the front
• delete an interior node
• delete the last node
Operations on a single linked list