• Introduction To Linked list
• Introduction To One Way Linked list
• Operations on One Way Linked List
Contents
2

Linked List
• A link list can be defined as the linear collection of
elements where each element is stored in a node.
• The linear order b/w elements is given by means of
pointers instead of sequential memory locations.
Introduction to Linked List
3

• Singular or one-way linked list.
•. Doubly or two-way linked list.
•. Circular linked list.
• Header linked list.
Types of Linked List
4

It is also known as singular linked list.
Each node has two parts:-
• The first part is known as info part which holds the element.
• Second part is known as next part which holds the address of
next node.
One Way Linked List
5

One Way Linked List
Info Address of next node
6

Operations of 1-Way Linked List
• Traversing a linked list.
• Searching an element in linked list
• Inserting an element in linked list
• Deleting an element in linked list
• Copying a linked list.
• Merging two linked lists
• Splitting linked list into further parts.
7

Traversing A Linked List
Traversing a linked list refers to visiting each node of the list
in order to process the elements stored in the nodes.
Example:- list of students with roll no.
401 402 Null414
401 402 414
8
Begin

Algorithm : Traversal of linked list
Step1.If Begin=Null then
Print ”linked list is empty”
Exit
[End If]
Step2. Set Pointer =Begin
Step3.Repeat While Pointer ≠ Null
a. print : Pointer → Info
b. Assign Pointer =Pointer → Next
[End loop]
Step4.Exit
9

• In searching we traverse the list from begin and compare the
elements stored in each node with the desired element to be
searched
• If match is found then the address of the node is returned
otherwise we proceed to next node
• If element not found till null then search unsuccessful
Searching In A Linked List
10

Searching In A Link List
11
Begin 104 102 103 Null
Pointer
102
Item found in link list
Item not matched

Algorithm :Searching a Linked List
Step1: If Begin = Null Then
Print:”Linked List is Empty”
Exit
[End If]
Step 2: Set Pointer = Begin
Step 3: Repeat While Pointer ≠ Null
If Pointer → info = Data Then
Print : “Element is found at address”:Pointer
Exit
Else
Set Pointer = Pointer → Next
[End If]
[End Loop]
Step 4: Print : “Element not found in linked list”
Step 5 :Exit
12

13
Memory Allocation/Deallocation
• Before we move on to insertion and deletion in a linked
list part let’s discuss about memory allocation and
deallocation.
• To insert an element into the linked list , the first we need
is to get a free node.
• In case of deletion of a node it is desired to return to
memory taken by deleted node for its reusability in future.

• First we get a free node from the free storage list
• Then element to be inserted is placed into the info part of the
node and pointers are set to add the new node at desired location
of list.
Insertion In Linked List
14

Insertion In Linked List (Continued)
Where we can insert element in linked list?
• At the beginning of linked list
• At end
• At a particular position in list
• In the sorted linked list
15

Insertion At Beginning
Begin 12 Null
Null414
400
Begin 401 88
16
New

Algorithm : Insertion At Beginning
Step 1: If Free = Null Then
Print : “Overflow: No free available for insertion”
Exit
[End if]
Step 2: Allocate Space to node New
(set New = Free And Free = Free → Next)
Step 3: Set New → Info = Data
Step 4: Set New → Next = Begin And Begin = New
Step 5: Exit
17

• If list is empty, store null value in next part of new node and insert
item in the info part
• If list is not empty, traverse list till end node.
• Store address of new node into next part of the last node of the
linked list and the next part set to null.
Insertion At End
Begin 401 402 Null414
405 Null
Pointer
18
New

Algorithm : Insertion At End
Print :”Overflow: No free space available for insertion”
Exit
[End If]
Step 2: Allocate space to node New
Set New = Free And Free = Free → Next
Step 3: Set New → Info = Data , New → Next = Null
Step 4: If Begin = Null Then
Begin = New
Exit
[End If]
Step 6: Repeat While Pointer → Next ≠ Null
[End Loop]
Step 7: Set Pointer → Next = New
Step 8: Exit 19

Insertion At A Particular Position
• Locate the position of the node after which we want to insert
the new node.
• 2 cases are there if location found and if not found
• Traverse till we not reach on desired loc.
• If we reach on desired loc. Then loc. Found insert element if
we reach on end but not find a loc. Yet then loc. Not found.
20

Insertion At Any Location
Begin 401 402 Null414
Item
New → Next=Pointer → Next
Pointer → Next=New
21
Pointer
New

Algorithm : Insertion At Any Location
22
Print : “Overflow: No free space available for insertion”
Exit.
[End If]
Step 3: Repeat While Pointer ≠Null And Pointer → Info ≠ Data
[End Loop]
Step 4: If Pointer = Null Then
Print: “The node containing element Data is not
present, so insertion is not possible.”

Else
Allocate space to node New
Set New=Free, Free=Free → Next, New → Info=Item
Set New → Next=Pointer → Next
Set Pointer → Next=New
[End If]
Step 5: Exit
23

Insertion In Sorted Linked List
• Find the position of the node after which new node has to be
inserted
• List can be sorted in ascending order and descending order
• In ascending order first we compare the element with the
first element if inserted element is small then it will inserted
at first position else comparing goes on in desc. Order it is
opposite.
24

Insertion In A Sorted Linked List
Begin 401 405 408 Null
403
Pointer
25
New

Algorithm : Insertion At Any Location In sorted Link List
26
Allocate Space to node New
Set New = Free and Free = Free → Next
Set New → Info = Item
Set New → Next = Begin and Begin = New
[End If]
Step 2: If Item < Begin → Info Then
Allocate Space to node New
Set New → Info = Item
Set New → Next = Begin and Begin = New
Exit
[End If]
Step 3: Set Pointer = Begin and Pointer2 = Begin → Next

Step 4: Repeat While Pointer2 ≠ Null and Item > pointer2 → Info
Set Pointer1 = Pointer2 and Pointer2 = Pointer2 → Next
[End loop]
Print : “No space for insertion , Allocation of space to node
New is not possible”
Exit
[End If]
Step 6: Allocate space to node New
Set New = Free and Free = Free → Next
Step 7: Set New → Info = Item
Step 8: If Pointer2 = Null Then
Set Pointer1 → Next = New and New → Next = Null
Else
Set New → Next = Pointer → Next
Set Pointer1 → Next = New
[End If]
Step 9: Exit 27

Deletion From Linked List
Deletion can be done in 3 ways:
• Deleting a node at the begin of link list
• Deleting a node at end.
• Del. A particular node in the linked list.
28

DELETION OF NODE FROM BEGIN OF LIST
• Deletion of a node at the begin of the list is a very simple operation
which can be done by changing the list pointer variable begin.
• Now begin will point to next node in the list.
• The space occupied by the deleted node is returned to the free storage
list.
29
Deleting A Node At Begin.
Free
414
Null
Begin 401 402 Null

Algorithm : Deletion At Beginning of the linked list.
Step 1: If Begin = Null then
Print: “linked list is already empty”
Exit
[End if]
Step 2: set Item = Begin → Info and Pos = Begin
Step 3: Begin = Begin → Next
Step 4:Pos → Next = Free and Free = Pos
Step 5:Exit
30

• For deleting the lost node from the given plinked list, it is
necessary to traverse the entire linked list for finding the
address of the preceding node of the last node i.e., address
of second last node.
• After finding the address of the second last node we will
store the address stored in the next part of the last node
into the next part of the second last node i.e. null will be
stored in the next part of the 2nd last node.
31
Deleting A Node At End

Deleting A Node At End
Free Null
Begin 402 Null414
Pointer1 → Next=Pointer2 → Next
Pointer2 → Next=Free
Free=Pointer2
401
32
Pointer1 Pointer2
Pointer1 = Begin
Pointer2 = Begin→Next
Pointer1 = Pointer2
Pointer2 = Pointer2 → Next
NULL

Algorithm : Deletion At End
Step 1:If Begin = Null Then
Print : “Linked List Empty”
Exit
[End If]
Step 2: If Begin → Next = Null Then
Set Data = Begin → info
Deallocate memory held by Begin
(Begin → Next = Free and Free = Begin)
Set Begin = Null
Exit
[End If]
Step 3: Set Pointer1 = Begin and Pointer2 = Begin → Next
Step 4: Repeat While Pointer2 → Next ≠ Null
Set Pointer1 = Pointer2 and Pointer2 = Pointer2 → Next
[End loop] 33

Step 5: Set Pointer1 → Next = Pointer2 →Next
Step 6: Set Data = Pointer2 → Info
Step 7: Deallocate memory held by Pointer2
(Pointer2 →Next = Free and Free = Pointer2)
Step 8:Exit
34

• For deleting a particular node from the linked list, the first
task is to find the address of the preceding node of nth
node to be deleted.
• To complete the task traverse the linked list from begin and
compare the info. Stored in node with item.
• Two pointers pointer1 pointer2 will be used while
traversing the list for locating the address of the node to be
deleted and address of it’s preceding node.
35
Delete A Particular Node From Link List

Deleting A Particular Node In Link List
Begin
25 17 8
Free
Null
Pointer1 → Next=Pointer2 → Next
Pointer2 → Next=Free
Free=Pointer2
4
Null
Pointer1 Pointer2
36

Algorithm: Deletion At Any Location
Step 1 :If Begin = Null Then
Print : “Linked List is Empty”
Exit
[End If]
Step 2: If Begin → Info = Item Then
Set Pos = Begin
Set Begin = Begin → Next
Pos Next = Free and Free = Pos
Exit
[End If]
Step 3: Set Pointer1 = Begin and Pointer2 = Begin → Next
Step 4: Repeat While Pointer2 ≠ Null and Pointer2 → Info ≠ Item
SET Pointer1 = Pointer2 and Pointer2 → Next
[End loop]
37

Print : “Node containing element item not found”
Exit
Else
Set Pointer1 → Next = Pointer2 → Next
[End If]
Step 6: Deallocate memory held by Pointer2
(Set Pointer2 → Next = Free and Free = Pointer2)
Step 7: Exit
38

Copy A Link List Into Other Link List
• Consider the linked list with its start pointer as begin1.For
copying this given linked list into another list, use a new
pointer variable begin2 for the list in which source list will be
copied.
• Initially we will store null in the list variable begin2.
• Now we will traverse the entire source list from begin to the
end by copying the contents to the new target.
39

Copy A Link List Into Other Link List
17 8
Begin1 25 17 Null388
Begin2 25 Null38
A Link List Is Copied
40
Pointer

Algorithm: Copying One Link List Into Another Link List
41
Step 1: If Begin1 = Null Then
Print: “Source List is Empty”
Exit
[End If]
Step 2: Set Begin2 = Null
Print: “Free space not available”
Exit
Else
Allocate memory to the node New
[End If]
Step 4: Set New → Info=Begin1 → Info And New → Next =Null
Step 5: Set Begin2 = New

Step 6: Set Pointer1=Begin1 → Next And Pointer2=Begin2
Step 7: Repeat While Pointer1 ≠ Null And Free ≠ Null
a. Allocate memory to node New
(New=Free And Free=Free → Next)
b. Set New → Info=Pointer1 → Info And New → Next=Null
c. Set Pointer2 → Next=New
d. Set Pointer1=Pointer1 → Next And Pointer2=New
[End Loop]
Step 8: If Pointer1 ≠ Null Then
Print: “List copied successfully”
Else
Print: “Not enough space to perform copy operation”
[End If]
Step 9: Exit
42

Merging Two Linked List
• There are number of applications where there is need to merge
two or more linked lists into a single linked list.
• Merging operation refers to putting the elements of two or more
lists into one list.
• The list can be sorted or unsorted.
Begin2 10 17 Null30
Begin1 25 27 Null42
43

After Merging
Begin
Merged Complete List
Begin2 10 Null30
Begin1 Null42
Pointer1
Pointer2
17
2725
10 17 25 27 30 Null42
44

Algorithm : Merging Two Sorted Linked List
Step 1: If Begin1=Null or Begin2=Null then
Print “one of the given linked list is empty”
Exit
[end if]
Step 2: If Free =Null then
Print: “no free space available”
Exit
Else
//Allocate memory to node New
Set New =Free and Free=Free → Next
[End If]
Step 3: Set Begin=Null
Step 4: If Begin1 → Info ≥ Begin2 → Info then
Set New → Info=Begin2 → Info and New → Next=Null
Set Pointer1=Begin1 and Pointer2=Begin2 → Next
45

Else
Set New → Info=Begin1 → Info and New → Next=Null
Set Pointer1=Begin1 → Next and Pointer2=Begin2
[End If]
Step 5: Set Begin=New and Pointer =New
Step 6: Repeat steps 7and 8 while Pointer1≠Null and Pointer2 ≠ Null
Step 7: If Free=Null then
Print “No free space available”
Exit
Else
Set New =Free and Free=Free → Next
[End If]
Step 8: If Pointer1 → Info ≥ Pointer2 → Info then
Set New → Info=Pointer2 → Info
Set New → Next=Null
Set Pointer → Next=New
Set Pointer=New and Pointer2=Pointer2 → Next 46

[End If]
[End Loop]
Step 9: If Pointer1=Null and Free ≠ Null then
Repeat while Pointer2 ≠ Null
a. Set New=Free and Free=Free → Next
b. Set New → Info=Pointer2 → Info and
New → Next =Null
c. Set Pointer → Next=New
d. Set Pointer =New and Pointer2=Pointer2 → Next
[End Loop]
Else
Repeat while Pointer1 ≠ Null
a. Set New=Free and Free=Free → Next
b. Set New → Info=Pointer1 → Info and
New → Next=Null
c.Set Pointer → Next=New
d. Set Pointer=New and Pointer1=Pointer1 → Next47

[End Loop]
[End If]
Step 10: If Pointer1 = Null And Pointer2=Null Then
Print: “The given link lists merged successfully”
Else
Print “Not Enough space”
[End If]
Step 11: Exit
48

Splitting Two Lists
• Suppose we have a linked list which we want to split into
lists.
• First we check total no. Of nodes then (N/2)th and (N/2+1)th
Node.
• After finding these addresses we will store null in the next
part of the (n/2)th node and address of (n/2+1)th node will be
stored in the new list pointer variable begin2.
• Now our list divide into 2 parts n/2 and n-n/2 with list
begin1 and begin2.
49

Splitted List1 And List2 .
17 2710 Null28
Begin
Begin2
27 28 Null32
Begin1
10 17 Null25
Pointer
50
3225

Algorithm: Split A Link List Into Two Link Lists.
51
Step 1: If Begin=Null
Print: “Splitting cannot be performed on empty list”
Exit
[End If]
Step 2: Set pointer = Begin And Count = 0
Step 3: Repeat Steps 4 and 5 While Pointer ≠ Null
Step 4: Set Count = Count + 1
Step 5: Set Pointer = pointer → Next
[End Loop]
Step 6: Set Mid = Integer(count/2)
Step 7: Set Begin2 = Null And Pointer = Begin And i =1
Step 8: Repeat Step 9 While i ˂ Mid

Step 9: Set Pointer = Pointer → Next
Set i = i +1
[End Loop]
Step 10: Set Begin2 = Pointer → Next And
Pointer → Next = Null
Step 11: Exit
52

Reversing A One Way Linked List
• To reverse a linked list, we need to use three pointers
variables.
• One pointer variable is used to store the address of current
node.
• Second pointer variable will be used to store the address of
next node.
• The third pointer variable will be used to store the address of
next to next of current node.
53

Reversing A One Way Linked List
Begin2
105 Null
Begin1
5 Null10
54

Reverse Link List With More Than Two Nodes
17 2725Null10 4228
Begin
17 272510 Null4228
Begin
55

Algorithm: Reverse The One Way Link List
56
Print: “No node is present in link list”
Exit
[End If]
Step 2: If Begin Next = Null Then
Print: “link list is having only one node”
Exit
[End If]
Step 3: If Begin → Next ≠ Null Then
Set Pointer1 = Begin
Set Pointer2 = Begin → Next
Set Pointer3 = Pointer2 → Next
[End If]

Set Pointer2 → Next = Pointer1
Set Pointer1 → Next = Null
Set Begin = Pointer2
Exit
[End If]
Step 5: Set Pointer1 → Next=Null
Step 6: Repeat steps 7 to 10 while Pointer3 → Next ≠Null
Step 7: Set Pointer2 → Next=Pointer1
Step 8: Set Pointer1=Pointer2
Step 9: Set Pointer2=Pointer3
Step 10: Set Pointer3=Pointer3 → Next
[End Loop]
Step 13: Set Begin=Pointer3
Step 14: Exit 57

Ppt of operations on one way link list

More Related Content

What's hot (20)

Viewers also liked (6)

Similar to Ppt of operations on one way link list (20)

Recently uploaded (20)

Ppt of operations on one way link list