3. Course contents
Circular Link List
Data Structure (Declaration, Initialization, Updating)
Insert After a specific location
Insert a value before a specific location
Insert a value as a first item of list
Delete a value from a link list
4. Circular Link list
A circular linked list is a type
of linked list in which last
node of the list points to
start node of the list instead
of NULL.
data data
data
data
data
data
data
start
next next
next
next
next
next
next
5. Circular Link list
Circular linked list contains all the operations that a simple linked list has
The only difference is that ‘next’ pointer of last node points to first (start) node
of list
This small change gives the list a circular form affecting the implementation of
few operations in the list including add_node(), insert_node(), append_node(),
delete_node() etc
Except when list is empty, no node pointer points to NULL
8. Circular Linked list … Operations
Operation Description Pseudocode
Clist(); A constructor that sets
‘start’ pointer to NULL
Assign NULL to ‘start’
int size(); Calculate and return the
number of elements in list
If ‘start’ points to NULL, return 0
Otherwise,
Create a variable ‘count’ and assign 1 to it
Create a node pointer ‘temp’ and point it
to next of ‘start’
Iterate through all list items until ‘temp’
points to ‘start’ again; at that point current
value of ‘count’ will be returned
During every iteration ‘count’ will be
incremented by 1 and ‘temp’ will point to
‘next’ pointer of node currently it is
pointing to
10. Circular Linked list … Operations
Operation Description Pseudocode
void print_all(); Prints all nodes’ data
values
Assign ‘start’ to a Node pointer named ‘temp’
Traverse through the list until either ‘temp’
reaches to the ‘start’ of CList again
During every iteration print the ‘data’ value
12. Circular Linked list … Operations
Operation Description Pseudocode
Node* search(int key); Searches through the list
for a Node with given value
and returns its reference
Create a new node pointer ‘temp’ and point it
to ‘start’
Traverse through the list until either ‘temp’
reaches to the Node with value equal to ‘key’ or
it reaches to the ‘start’ of list again
If ‘temp’ reaches to the ‘start’ of CList again,
return NULL
Otherwise, return the node pointer ‘temp’
14. Circular Linked list … Operations
Operation Description Pseudocode
void add_node(int); Create a node with given
value and add it
immediately after the start
of the list
Create a node with given ‘key’ as its ‘data’
pointed by a node pointer ‘temp’ and set its
‘next’ to itself
If size() of CList is equal to 0, assign ‘temp’ to
‘start’
Otherwise,
Set ‘next’ of ‘temp’ to ‘next’ of ‘start’
Assign ‘temp’ to ‘next’ of ‘start’
16. Circular Linked list … Operations
Operation Description Pseudocode
void append_node(int); Create a node with given
value and append (add to
end) it to the list
Create a node with given ‘key’ as its ‘data’
pointed by a node pointer ‘n’ and set its ‘next’
to itself
Create a node pointer ‘temp’ and point it to
‘start’ of Clist
If size() of CList is equal to 0,
Assign ‘n’ to ‘start’, Exit
Otherwise,
Traverse ‘temp’ to the last node of Clist
Set ‘next’ of ‘n’ to ‘start’
Set ‘next’ of ‘temp’ to ‘n’
Exit
18. Circular Linked list … Operations
Operation Description Pseudocode
void insert (int after, int
key);
Insert a node with given
value in linked list
immediately after a specific
node already present in the
list
Create a new node pointer ‘temp’ and assign
‘start’ to it
If ‘start’ is pointing to NULL, Exit
Move to next nodes until either ‘temp’ reaches
to the node with ‘data’ value equal to ‘after’ or
it reaches to ‘start’ of CList again
If ‘temp’ is pointing to ‘start’ of CList again,
exit
Else,
Create a new node in memory with ‘key’
as data and point it by a pointer ‘n’
Set ‘next’ of ‘n’ to ‘next’ of ‘temp’
Set ‘next’ of ‘temp’ to ‘n’
Exit
20. Circular Linked list … Operations
Operation Description Pseudocode
void delete_node
(int key);
Delete the node with
given value from the list
If size() of CList is 0, Exit
Create a node pointer ‘temp’ and point it to ‘start’
Iterate ‘temp’ to next nodes until either ‘temp’ reaches to a
node whose ‘next’ node has ‘data’ equal to ‘key’ or its ‘next’
node is ‘start’
If ‘next’ of ‘temp’ points to ‘start’
If ‘data’ of ‘start’ is not equal to ‘key’, Exit
Else if size() of CList is equal to 1
Assign NULL to ‘start’, Exit
Otherwise
Move ‘start’ to next node in list
Assign ‘next’ of ‘temp’ to a node pointer, say ‘x’
Set ‘next’ of ‘temp’ to ‘start’
Delete ‘x’
Exit
Else,
Delete ‘next’ pointer of ‘temp’ and adjust pointers
accordingly
Exit
22. Structure of Node in CLL
struct node
{
int data;
struct node*link;
};
23. Main Operations on CLL
#include<iostream>
#include<stdlib.h>
#define null 0
#define true 1
using namespace std;
struct node{
int data;
struct node*link;
};
struct node*ptfirst=null;
void insert(int value);
void display();
void insert_first(int value);
void insert_after(int position,int value);
void insert_before(int position,int value);
void Delete(int value);
int main(){
int opt_no,value,position;
24. while(true){
cout<<"Enter 1 for insert"<<endl;
cout<<"Enter 2 for Display"<<endl;
cout<<"Enter 3 for insert first"<<endl;
cout<<"Enter 4 for insert after"<<endl;
cout<<"Enter 5 for insert before"<<endl;
cout<<"Enter 6 for delete"<<endl;
cout<<"Enter 7 for Exit"<<endl<<endl;
cout<<"Now Enter Option Number: ";
cin>>opt_no;
25. switch (opt_no)
{
case 1:
cout<<"insert value: ";
cin>>value;
cout<<endl;
insert(value);
break;
case 2:
display();
break;
case 3:
cout<<"insert value: ";
cin>>value;
cout<<endl;
insert_first(value);
break;
case 4:
cout<<"enter position: ";
cin>>position;
cout<<"insert value: ";
cin>>value;
cout<<endl;
insert_after(position,value);
break;
26. case 5:
cout<<"enter position: ";
cin>>position;
cout<<"insert value: ";
cin>>value;
cout<<endl;
insert_before(position,value);
break;
case 6:
cout<<"insert value: ";
cin>>value;
cout<<endl;
Delete(value);
break;
case 7:
exit(1);
default:
cout<<"I N V A L I D ___ O P T I O N"<<endl;
}
27. Insert a Value in CLL
void insert(int value)
{
struct node*temp;
if(ptfirst==null){
temp=(struct node*)malloc(sizeof(node));
ptfirst=temp;
}
else{
temp=ptfirst;
do{
temp=temp->link;
}while(temp->link!=ptfirst);
temp->link=(struct node*)malloc(sizeof(node));
temp=temp->link;
}
temp->link=ptfirst;
temp->data=value;
return;
}
28. Delete a value from a CLL
void Delete(int value){
if(ptfirst==null){
cout<<"No value in the list to delete."<<endl;
return;
}
struct node*temp;
struct node*prev;
temp=ptfirst;
prev=temp;
do{
if(temp->data==value){
if(temp==ptfirst && temp->link==ptfirst){
delete temp;
ptfirst=null;
return;
}
else if(temp==ptfirst){
36. Course contents
Double Circular Link List
Data Structure (Declaration, Initialization, Updating)
Insert After a specific location
Insert a value before a specific location
Insert a value as a first item of list
Delete a value from a link list
37. Double circular Linked list
Double circular linked list is a type of linked list with every node
containing two node pointers (next, prev). Moreover next link of
end node points to start node and prev link of start node points
to end node.
41. Double circular Link list … Operations
Operation Description Pseudocode
DList(); A constructor that sets
‘start’ pointer to NULL
Assign NULL to ‘start’
Assign NULL to ‘end’
42. Double circular Link list … Operations
Operation Description Pseudocode
int size(); Counts and returns the
number of nodes in double
linked list
Create a Node Pointer ‘temp’ and point it to
‘start’
If ‘temp’ points to NULL
Return 0, Exit
Otherwise,
Create a variable ‘count’ and assign 1 to it
Iterate through list nodes until ‘temp’
points to ‘start’ again
During each iteration increase value of
‘count’ by 1 and move to ‘next’ node
When ‘temp’ points to ‘start’ again, return
‘count’, Exit
44. Double circular Link list … Operations
Operation Description Pseudocode
void print_all(); Prints all nodes’ data
values
Create a node pointer ‘temp’ and point it to ‘start’ of
list
Traverse through the list until ‘temp’ reaches to the
‘start’ of list again
During every iteration print the ‘data’ value and move
to ‘next’ node
46. Double Linked list … print_all_backward()
Operation Description Pseudocode
void print_all_backward(); Print all nodes’ ‘data’ values
in backward direction
Create a node pointer ‘temp’ and point it to
‘end’ of list
Traverse back through the list until ‘temp’
reaches to the ‘end’ node of the list again
During every iteration print the ‘data’ value and
move to previous node
48. Double circular Linked list … SEARCH()
Operation Description Pseudocode
Node* search(int key); Searches through the list
for a Node with given value
and returns its reference
Create a node pointer ‘temp’ and point it to
‘start’
Traverse through the list until either ‘temp’
reaches to the Node with given value or it
reaches to the ‘start’ of list again
If ‘temp’ points to ‘node’ with its ‘data’ equal to
‘key’ then return ‘temp’ reference
Otherwise, return NULL
50. Double Linked list … Operations
Operation Description Pseudocode
void add_node(int key); Create a node with given
value and add it to start of
the list
Create a node with given ‘key’ as its ‘data’,
NULL as ‘next’, NULL as ‘prev’
Point the newly created node with pointer
‘temp’
If size() of list is ZERO, assign ‘temp’ to ‘start’,
assign ‘temp’ to ‘end’, assign ‘next’ of ‘temp’ to
‘temp’ and ‘prev’ of ‘temp’ to ‘temp’
Otherwise
Assign ‘start’ to ‘next’ of ‘temp’
Assign ‘end’ to ‘prev’ of ‘temp’
Assign ‘temp’ to ‘next’ of ‘end’
Assign ‘temp’ to ‘prev’ of ‘start’
Assign ‘temp’ to ‘start’
52. Double Linked list … Operations
Operation Description Pseudocode
void append_node(int
key);
Create a node with given
value and add it to end of
the list
Create a node with given ‘key’ as its ‘data’,
NULL as ‘next’, NULL as ‘prev’
Point the newly created node with pointer
‘temp’
If size() of list is ZERO, assign ‘temp’ to ‘start’,
assign ‘temp’ to ‘end’, assign ‘next’ of ‘temp’ to
‘temp’ and ‘prev’ of ‘temp’ to ‘temp’
Otherwise
Assign ‘start’ to ‘next’ of ‘temp’
Assign ‘end’ to ‘prev’ of ‘temp’
Assign ‘temp’ to ‘next’ of ‘end’
Assign ‘temp’ to ‘prev’ of ‘start’
Assign ‘temp’ to ‘end’
54. Double Linked list … Operations
Operation Description Pseudocode
void delete_node
(int key);
Delete the node with
given value (key) from
the list
Search node with given value as key (say it is ‘temp’)
If ‘temp’ is equl to NULL then Exit
Else If ‘temp’ is equal to ‘start’ and it is equal to ‘end’
Assign NULL to ‘start’ and assign NULL to ‘end’, Exit
Else if ‘temp’ is equal to ‘start’
Assign ‘start’ to ‘next’ of ‘start’
Assign ‘end’ to ‘prev’ of ‘start’
Assign ‘start’ to ‘next’ of ‘end’
Delete ‘temp’, Exit
Else if ‘temp’ is equal to ‘end’
Assign ‘end’ to ‘prev’ of ‘end’
Assign ‘start’ to ‘next’ of ‘end’
Assign ‘end’ to ‘prev’ of ‘start’
Delete ‘temp’, Exit
55. Double Linked list … Operations
Operation Description Pseudocode
void delete_node
(int key);
Delete the node with
given value (key) from
the list
Otherwise,
Create node pointers ‘n’ and ‘p’ and assign them ‘next’ of
‘temp’ and ‘prev’ of ‘temp’ respectively
Assign ‘n’ to the ‘next’ of ‘p’
Assign ‘p’ to the ‘prev’ of ‘n’
Delete ‘temp’, Exit
57. Double Linked list … Operations
Operation Description Pseudocode
void insert_after(int after,
int key);
Insert a node with given
value in linked list
immediately after a specific
node already present in the
list
Search the node with data is equal to ‘after’, say
it is ‘temp’
If ‘temp’ is pointing to NULL,
exit
Else,
Create a new node in memory and point it
be a pointer ‘new_node’
Set ‘key’ as data of ‘new_node’
Assign ‘next’ of ‘temp’ to ‘next’ of ‘new_node’
Assign ‘temp’ to ‘prev’ of ‘new_node’
Assign ‘new_node’ to ‘prev’ of ‘next’ of
‘temp’
Assign ‘new_node’ to the ‘next’ of ‘temp’
If ‘temp’ points to ‘end’, Assign ‘new_node’
to ‘end’
Exit
59. Double Linked list … Operations
Operation Description Pseudocode
void insert_before(int
before, int key);
Insert a node with given
value in linked list
immediately after a
specific node already
present in the list
Search the node with data is equal to ‘before’, say
it is ‘temp’
If ‘temp’ is pointing to NULL,
exit
Else,
Create a new node in memory and point it be
a pointer ‘new_node’
Set ‘key’ as data of ‘new_node’
Assign ‘temp’ to ‘next’ of ‘new_node’
Assign ‘prev’ of ‘temp’ to ‘prev’ of ‘new_node’
Assign ‘new_node’ to ‘next’ of ‘prev’ of ‘temp’
Assign ‘new_node’ to the ‘prev’ of ‘temp’
If ‘temp’ points to ‘start’, Assign ‘new_node’ to
‘start’
Exit
62. Main operations on DCLL
#include<iostream>
#include<stdlib.h>
#define null 0
#define True 1
using namespace std;
struct node{
struct node*prev;
int data;
struct node*next;
};
struct node*ptfirst=null;
void insert(int value);
void display();
void insert_first(int value);
void insert_after(int value, int position);
void insert_before(int value, int position);
void Delete(int value);
63. int main(){
int value,position,option;
while(True){
cout<<endl;
cout<<"Enter Option Number: "<<endl;
cout<<"1 to Insert a value."<<endl;
cout<<"2 to Display the list."<<endl;
cout<<"3 to Insert at First."<<endl;
cout<<"4 to Insert after a specific value."<<endl;
cout<<"5 to Insert before a specific value."<<endl;
cout<<"6 to Delete a value."<<endl;
cout<<"7 to EXIT"<<endl;
cin>>option;
64. switch(option){
case 1:
cout<<endl<<"Enter a Value: "<<endl;
cin>>value;
insert(value);
break;
case 2:
display();
break;
case 3:
cout<<endl<<"Enter a Value: "<<endl;
cin>>value;
insert_first(value);
break;
case 4:
cout<<endl<<"Enter a Value: "<<endl;
cin>>value;
cout<<"Enter the Position: ";
cin>>position;
insert_after(value,position);
break;
65. case 5:
cout<<endl<<"Enter a Value: "<<endl;
cin>>value;
cout<<"Enter the Position: ";
cin>>position;
insert_before(value,position);
break;
case 6:
cout<<endl<<"Insert Value to Delete: "<<endl;
cin>>value;
Delete(value);
break;
case 7:
exit(0);
break;
default:
cout<<endl<<"INVALID OPTION"<<endl;
}
}
return 0;
}
