1. UNIT-II Topics to be covered Singly linked list Circular linked list
Doubly linked list
Representing Stack with linked list
Representing Queues with linked list

2. In array elements are stored in consecutive memory locations
In array elements are stored in consecutive memory locations. To occupy the adjacent space, block of memory that is required for the array should be allocated before hand.
Once memory allocated it cannot be extended any more. So that array is called the static data structure.
Wastage of memory is more in arrays.

3. What’s wrong with Array and Why lists?
Disadvantages of arrays as storage data structures:
slow searching in unordered array
slow insertion in ordered array
Fixed size
Linked lists solve some of these problems
Linked lists are general purpose storage data structures and are versatile.

4. Linked list is able to grow in size as needed
Array has a fixed size
Data must be shifted during insertions and deletions
Linked list is able to grow in size as needed
Does not require the shifting of items during insertions and deletions.

5. Linked Lists

6. Linked list\singly linked list
It is a dynamic data structure where amount of memory required can be varied during its use.
A linked list consists of a collection of elements called nodes linked together by pointers.
In linked list, adjacency between the elements are maintained by means of links or pointers.

7. Linked List Collection of links with reference to the first.
Each link (node) has
Data Part: part to store data
Link Part :link that refers to the next
node in the list.
Data part of the node can be an integer, a character, a String or an object of any kind.

8. Node
Head Node

9. Classification of linked list
Depending on the requirements the pointers are maintained, and accordingly linked list can be classified into three groups.
Single linked list
Circular linked list
Double linked list\doubly linked list.

10. Singly Linked Lists
A linked list is an ordered collection of homogeneous data elements called nodes where linear order is maintained by means of links and pointers.
Each node stores
Element\data(may be integer, char or string)
link to the next node
next
node
elem
Start
Null A B C D

11. single linked list First link has dummy value for data
reference to next link refers to the first link that hold information
Last link does not refer to the next one.
Reference to the next link is null

12. Operations on singly linked list
Insertion
Deletion
Traverse
Search

13. Insertion in linked list
There are various positions where node can be inserted.
Insert at front ( as a first element)
Insert at end ( as a last node)
Insert at middle ( any position)

14. Insert new node at front in linked list
Algorithm
step1- create a new node
Step2- new->link=header->link
Step3- new->data=item
Step4- header->link=new.
Step5-stop

15. header
Null 10 20 30 2 2 1 1 5
Newnode

16. Insert new node at end of the linked list
Algorithm
Step1- create a new node
Step2- ptr=header
Step3- while(ptr->link!=null)
3.1. ptr=ptr->link
Step4- ptr->link=new
Step5- new->data=item
Step6- new->link=null
Step7-stop

17. header
ptr
Null 10 20 30 1 40
Newnode

18. Insert new node at any position in linked list
Algorithm
1.Create new node
2. ptr=header
3. while((ptr->data!=key)&&(ptr->link!=null)
3.1 ptr=ptr->link
4. if(ptr->link=null
4.1.print key is not found in the list
5. Else
5.1 new->link=ptr->link
5.2 new->data=item
5.3. ptr->link= new
6. End if
7. stop.

19. ptr
header
Null 10 20 30 2 1 5
Newnode

20. Deletion of a node from ll
Like insertion, there are also various cases of deletion:
Deletion at the front
Deletion at the end
Deletion at any position in the list

21. 1.Deletion at the front Algorithm ptr=header->link If( ptr==NULL)
2.1 print “the list is empty”
3. else
3.1 ptr1=ptr->link
3.2 header->link=ptr1
3.3 return ptr
4. End if
5. stop

22. header
Null
KEY 20 30
ptr
ptr1

23. 2. Deletion at the end Algorithm 1.ptr=header
2. if(ptr->link==NULL)
2.1 print “ the list is empty”
3. Else
3.1 while(ptr->link!=NULL)
3.2 ptr1=ptr
3.3 ptr=ptr->link;
3.4 end while
4 ptr1->link=NULL
4.1 return ptr
4. End if
5. stop

24. ptr
header
ptr1
Null
KEY 20 30

25. 3. Deletion at any position
Algorithm
ptr1=header
ptr=ptr1->link
While(ptr!=NULL)
3.1 if(ptr->data!=key)
3.2 ptr1=ptr
3.3 ptr=ptr->link
4. Else
4.1 ptr1->link=ptr->link
4.2 return ptr
5. End while
6. If (ptr==NULL)
6.1 print “key does not exist”
7. stop

26. ptr1
header
ptr
Null 10
KEY 30