The document discusses circular singly linked lists. It begins by explaining the issue with singly linked lists, which is that nodes cannot be revisited. It then introduces circular singly linked lists as a solution. It describes the memory representation of a circular linked list using node pointers. It lists common operations on circular linked lists like insertion, deletion, searching and display. It provides examples of creating a new list, inserting nodes at the beginning and end, and deleting nodes from the beginning and end. It notes that a tail pointer should be used instead of the head pointer for certain operations.

1. DATA STRUCTURES
Dr. P. Subathra
subathrakishore@yahoo.com
Professor
Dept. of Information Technology
KAMARAJ College of Engineering & Technology
(AUTONOMOUS)
Madurai
Tamil Nadu
India

2. CS8391 – DATA STRUCTURES
ONLINE CLASSES – CLASS NO. 9
04.09.2020
(10:00 PM – 12:00 Noon)

3. UNIT 1
CIRCULAR SINGLY LINKED LIST

4. WHAT IS WRONG WITH
SINGLY LINKED LIST…??

5. CANNOT REVISIT THE NODES AGAIN IN THE
LIST….???!!!
WHAT IS WRONG WITH
SINGLY LINKED LIST…??

6. • Is that Annoying….???
• No Worries MAN…!!!
WHAT IS WRONG WITH SINGLY LINKED
LIST…??

7. CIRCULAR SINGLY LINKED LIST….!!!

8. Node of a Circular Linked List
• NODE
– Data Field
– Link / Pointer Field
• HEADER…???!!!
• NULL Pointer

9. SIMILARITY IN BOTH LISTS
1. SINGLY LINKED LIST
2. CIRCULAR SINGLY LINKED LIST

10. CIRCULAR SINGLY LINKED LIST

11. MEMORY REPRESENTATION

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13. 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
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1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
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header

14. 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
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header

16. Operations on a Singly Circular Linked List
• Creating a new list
• Insertion
- at the beginning
- at the end
- after and element
- before an element
• Deletion
- at the beginning
- at the end
- a given element
- at a position
• Display
• Search Element
• etc ………………

17. NODE CREATION

18. CREATING A LIST
• Creating the FIRST Node and Attaching it to
the List
struct node * temp = (node *) malloc (sizeof (struct node));
head = temp;
tempnext = NULL
Operations on a Singly Linked List
NULL
head
Data field Link field
temp1005

19. Creating a New List
struct node * temp = (node *) malloc (sizeof (struct node));
tempdata =222;
head = temp;
tempnext = head; (or) headnext=head;
1005
head
Data field Link field
1005
temp1005
222
CIRCULAR SINGLY LINKED LIST : CREATING A LIST

20. INSERT FIRST

22. INSERT LAST

24. DELETE FIRST

26. DELETE LAST

28. POINTS TO NOTE IN CIRCULAR SINGLY LINKED LIST
INSERT LAST
Order of Insertion : 5,6,7, 8

29. POINTS TO NOTE IN CIRCULAR SINGLY LINKED LIST
INSERT FIRST
Order of Insertion : 5, 6,7, 8

30. USE A TAIL INSTEAD OF HEAD

31. USE A TAIL INSTEAD OF HEAD

32. USE A TAIL INSTEAD OF HEAD

33. USE A TAIL INSTEAD OF HEAD

34. void insertLast(int item)
{
struct node *temp = (struct node *)malloc(sizeof(struct node));
struct node *temp;
temp->next=last;
last=temp;
printf("nNode Inserted Lastn");
}
Circular Singly Linked List: Insert Last

35. void insertFirst( int item)
{
struct node * temp = (struct node *)malloc(sizeof(struct node));
temp->data=item;
temp->next=last;
printf("nNode Inserted Firstn");
}
Circular Singly Linked List: Insert First

36. int deleteLast(int item)
{
struct node *temp;
int x= last(x);
temp-=last;
last=last->next;
free (temp);
temp=NULL;
printf("n Deleted Firstn");
return (x);
}
Circular Singly Linked List: Delete First

37. int deleteLast(int item)
{
struct node *temp; struct node * curr;
If(last==NULL) {Printf(“n no node to delete”);}
Else If(last->next==last)
{ x= last->data; Temp=last; Last=NULL; Free(temp); temp=NULL; return(x) }
Else
{
prev=last;
while(prev->next !=last)
prev=prev->next;
prev->next=last->next;
temp = last; x=last->data;
last= prev;
printf("n Deleted Lastn");
return (x);
}
Circular Singly Linked List: Delete Last