1. 3 singly linked list insertion 2

DATA STRUCTURES
Dr. P. Subathra
Professor
Dept. of Information Technology
KAMARAJ College of Engineering & Technology

CS8391 – DATA STRUCTURES
ONLINE CLASSES – CLASS NO. 3
18.08.2020
(04:00 PM – 05:00 PM)

INSERT AFTER AN ELEMENT
Algorithm :
• STEP 1 : Dynamically generate a new node.
• STEP 2 : Get the value in the node’s data field.
• STEP 3 :
i. Check if the list is empty, if so display a message and
return.
ii. Traverse the list until the specified node is reached
or End of List is reached.
a. If element is found, insert the new element after the
current node
b. Else if end of list is reached, display a message of
ELEMENT NOT FOUND and return

• Initial List
• Insert 8 after 6

• Initial List
• Insert 8 after 6
• Final List

ALGORITHM
STEP 1 : Dynamically generate a
new node.
STEP 2 : Get the value in the
node’s data field.
CODE & ILLUSTRATION

ALGORITHM
STEP 3:
i. Check if the list is empty,
if so, display a message and
return
CODE & ILLUSTRATION
if (head==NULL)
{
prinft(“Empty List”);
return(); //optional
}
NULL
head

ALGORITHM
STEP 3 :
ii. Else traverse the list until the
specified node is reached or
End of List is reached.
a. If element is found, insert the
new element after the current node
b. Else if end of list is reached,
display a message of ELEMENT NOT
FOUND and return
CODE & ILLUSTRATION
else
{
node * current = head;
while (current  data ! = searchElement
|| currentnext!=NULL)
{
current = current  next;
}
}

ALGORITHM & CODESTEP 3 :
ii. Else traverse the list until the specified node
is reached or End of List is reached.
a. If element is found, insert the
new element after the current node
b. Else if end of list is reached,
display a message of ELEMENT NOT
FOUND and return
ILLUSTRATION
else
{
node * current = head; while (current  data ! = searchElement
|| currentnext!=NULL) { current = current  next; }
if ( current data == element)
{
tempnext=current->next;
currentnext=temp;
}
else
printf(“Element not found”);
}

INSERT BEFORE AN ELEMENT
Algorithm :
• STEP 1 : Dynamically create a new node
• STEP 2 : Get the value in the data field of the new node.
• STEP 3:
i. Check if the list is empty, if so display a message and return.
ii. Check if the node is available as the first node
a. Perform Insert First operation
iii. Traverse the list until the specified node is reached or End of
List is reached. While traversing, keep track of the previous
node also.
a. If element is found, insert the new element after the previous node
b. Else if end of list is reached, display a message of ELEMENT NOT
FOUND and return

ALGORITHM
new node.
CODE & ILLUSTRATION

ALGORITHM
STEP 3:
return
CODE & ILLUSTRATION
if (head==NULL)
{
return(); //
}
NULL
head

ALGORITHM & CODE
STEP 3:
ii. Else check if the node is
available as the first node
(eg) Insert after 7
ILLUSTRATION
else if (head-> data==element)
{
temp->next=head;
head=temp;
}
NULL
NULL
NULL

ALGORITHM & CODE
STEP 3:
iii. Else Traverse the list until the specified node is
reached or End of List is reached. While
traversing, keep track of the previous node
also.
ILLUSTRATION
else
{
node * previous=head;
node * current = head-> next;
while (current->data! = element
|| current->next!=NULL)
{
current= current-> next;
previous = previous->next;
}
}

ALGORITHM & CODE
STEP 3: iii.
a. If element is found, insert the new
element after the previous node
b. Else if end of list is reached, display a
message of ELEMENT NOT FOUND
ILLUSTRATION
else
{
node * previous=head;
node * current = head-> next;
while (current->data! = element
|| current->next!=NULL)
{
previous = previous->next;
}
if(current->data==element)
{
temp->next=prev->next;
prev->next = temp;
}
else
printf(“Element not found”);
}

INSERT AT A POSITION
Algorithm :
STEP 1 : Dynamically create a new node.
STEP 2 : Read the new value into the element field of the new node.
STEP 3:
Let k= POSITION
i. Check if the list is empty, if so display a message and return.
ii. Check if k==1 (First Position)
iii. Traverse the list until the specified (k -1)th node is reached or End
of List is reached
a. If (k -1) is available in the list, then, insert the new element after the (k -1)th
node
Copy the (k-1)th nodes next field value into the next field of the new node.
Make the (k-1)th node to point to this new node.
b. Else if end of list is reached, display a message of ELEMENT NOT FOUND and
return

ALGORITHM
new node.
CODE & ILLUSTRATION

ALGORITHM
STEP 3:
return
CODE & ILLUSTRATION
if (head==NULL)
{
return(); //
}
NULL
head

ALGORITHM & CODE
STEP 3:
ii. Check if k==1 (First Position)
ILLUSTRATION
else if (k== 1)
{
temp->next=head;
head=temp;
}
NULL
NULL
NULL

ALGORITHM & CODE
STEP 3:
iii.
Traverse the list until the specified (k -1)th
node is reached or End of List is reached
(eg) Let Position = 3
ILLUSTRATION
else
{
count =1; k = position;
current = head;
while (count <=(k-1) ||
current->next!=NULL)
{
count++;
}
}

ALGORITHM & CODE
STEP 3:
iii.
ILLUSTRATION
else
{
current = head;
{
count++;
}
temp->next = current-> next;
current-> next = temp
}

ALGORITHM & CODE
STEP 3:
iii.
ILLUSTRATION
else
{
current = head;
{
count++;
}
}
NULL

ALGORITHM & CODE
STEP 3:
iii. Traverse the list until the specified (k -1)th
ILLUSTRATION
else
{
current = head;
{
count++;
}
temp->next = current-> next;
current-> next = temp
}
NULL
NULL
NULL
NULL
NULL

1. 3 singly linked list insertion 2

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