1. 2 Singly Linked List

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

2. CS8391 – DATA STRUCTURES
ONLINE CLASSES – CLASS NO. 2
13.08.2020
(10:00 AM – 11:00 AM
&
11:30 AM – 12:30 PM)

3. UNIT 1
SINGLY LINKED LIST

4. WHAT IS WRONG WITH ARRAY…??

5. • STATIC MEMORY ALLOCATION
• BUT… IS IT NOT DYNAMIC…??
• malloc ( )
WHAT IS WRONG WITH ARRAY…??

6. • malloc ( ) …………NO..!!!
• HOW ABOUT realloc( ) …???
• realloc ( )…. NO….??!!!
WHAT IS WRONG WITH ARRAY…??

7. HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050
LOOK CLOSER……

8. HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050
LOOK CLOSER……

9. int * a = (int *) malloc (4);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

10. int * a = (int *) malloc (4);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

11. int * a = (int *) realloc (8);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

12. int * a = (int *) realloc (4);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

13. int * a = (int *) realloc (4);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

14. int * a = (int *) realloc (4);
HEAP
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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

15. LINKED LIST….!!!

16. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

17. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

18. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

19. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

20. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

21. 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
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

22. Linked List
• NODE
– Data Field
– Link / Pointer Field
• HEADER
• NULL Pointer

23. TYPES OF LINKED LISTS
1. SINGLY LINKED LIST
2. CIRCULAR SINGLY LINKED LIST

24. TYPES OF LINKED LISTS
1. DOUBLY LINKED LIST
2. CIRCULAR DOUBLY LINKED LIST

25. Singly Linked List

26. Singly Linked List
• Linked list or list is an ordered collection of
elements.
• Each element in the list is referred as a node.
• Each node contains two fields namely.
– Data field.
– Link field.
(or) Address field

27. Operations on a Singly 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
• Reverse List
• Sort List
• Find Duplicates
• ………………

28. CREATING A LIST
• Template for a node
struct node
{
int element ;
struct node * next ;
};
• Creating an Empty List
struct node * head = NULL;
Operations on a Singly Linked List
NULL
head
Data field Link field
2 B 4 B
4 B
head

29. CREATING A LIST
• Creating a New 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

30. CREATING A LIST
• Creating a New Node and Attaching it to the
List
struct node * temp = (node *) malloc (sizeof (struct node));
tempnext = NULL
tempdata =222;
head = temp;
Operations on a Singly Linked List
1005
head
Data field Link field
NULL
temp
1005
222

31. INSERTION – FIRST
• Algorithm
STEP 1: Dynamically create a new node.
STEP 2: Read the element to the
element field of the new node.
STEP 3: Copy the address value
available in the Head pointer (also
called as Header) into the next field of
the new node.
STEP 4: Make the Header to pointer to
this new node.
• Case 1
– Insertion into an Empty
List
• Case 2
– Insertion into a Non
Empty List
Operations on a Singly Linked List

32. INSERTION – FIRST
• Algorithm
STEP 1: Dynamically create a new node.
STEP 2: Read the element to the
element field of the new node.
STEP 3: Copy the address value
available in the Head pointer (also
called as Header) into the next field of
the new node.
STEP 4: Make the Header to pointer to
this new node.
Case 1 – Empty List
Operations on a Singly Linked List

33. INSERTION – FIRST
• Algorithm
Case 2 : Non Empty List
STEP 1: Dynamically create a new node.
STEP 2: Read the element to the
element field of the new node.
STEP 3: Copy the address value
available in the Head pointer (also called
as Header) into the next field of the new
node.
STEP 4: Make the Header to pointer to
this new node.
Operations on a Singly Linked List

34. INSERTION – FIRST
Pseudo code
void InsertFirst (int x )
{
creat new node temp,
temp  element = x;
tempnext = header; // copy header value into T next
header = temp; // make header to point to new node T
}
Operations on a Singly Linked List

35. INSERTION – FIRST
Code Snippet in C
void InsertFirst (int x )
{
struct node * temp = (node*) malloc(sizeof(struct node*));
temp  data = x;
tempnext = head; // copy header value into T next
head = temp; // make header to point to new node T
}
Operations on a Singly Linked List

36. INSERTION – LAST
• Algorithm
STEP 1: Dynamically create a new node.
STEP 2: Read the element to the element
field of the new node and make the next field
to be NULL
STEP 3: If the list is empty insert this new
node as we did for insert first module
ie, make the header to point to this node.
STEP 4: If a non empty list already exist,
traverse the list till the last node is reached.
STEP 5: Make the last node to point to this
new node.
• Case 1
– Insertion into an Empty List
• Case 2
– Insertion into a Non Empty
List
Operations on a Singly Linked List

37. INSERTION – LAST
Algorithm : Case 1 - Empty
List
STEP 1: Dynamically create a new
node.
STEP 2: Read the element to the
element field of the new node and
make the next field to be NULL
STEP 3: If the list is empty insert this
new node as we did for insert first
module
ie, make the header to point to this
node.
Operations on a Singly Linked List

38. INSERTION – LAST
Algorithm :
Case 1 – Non Empty List
STEP 1: Dynamically create a new node.
STEP 2: Read the element to the element
field of the new node and make the next field
to be NULL
STEP 3: If the list is empty insert this new
node as we did for insert first module
ie, make the header to point to this node.
STEP 4: If a non empty list already exist,
traverse the list till the last node is reached.
STEP 5: Make the last node to point to this
new node.
Operations on a Singly Linked List

39. Insert Last – Non empty list

40. ALGORITHM Insert Last
void InsertLast (int x )
{
create a new node temp
temp  data = x;
tempnext = NULL;
if (head== NULL) // List is empty
{
head = temp;
}
else
{ / * List Traversal * /
node * current = head;
while (current next! = NULL) // Traverse to the last node.
current = current next;
current  next = temp ; // make last node to point to temp
}
}
Operations on a Singly Linked List