Circular linked list
A linked list in which the last node points to the first node instead of containing null pointer will be termed as circularly linked list or simply circular list
Circular linked list in data structures have an advantages over singly linked list. It is concerned with the accessibility of a node. Ina circular list every node is accessible from a given node that is, from this given node all nodes can be reached by changing through the list.
Insertion operation:
- Insertion as a first node:
cur
1= Head;
Head=cur;
ptr 1=Head;
(ii) Insertion after a given node:
cur link = ptr à link;
ptr1 link =cur;
Deletion Operation
Deleting first node
Head =ptr1 link;
ptr link =Head;
free(ptr);
- Deleting a specific node
temp=ptrl link;
ptr1 link = ptr1 link à link
free(temp);
Circular linked list Program in Data Structures
Implementaton of circular linked list
# include <studio.h>
#include <conio.h>
# define NULL
#include<stdlib.h>
struct Node
{
int data;
struct Node*link;
};
struct node*Head;
void create()
{
int a;
struct Node * cur,*ptr;
Head=NULL;
printf(“Enter Data For The Node(-1):”);
scanf(“%d%,&a);
while(a!=-1)
{
cur =(struct Node *) malloc (size of (struct Node));
curdata =a;
cur link =NULL;
if(Head== NULL)
Head==cur;
else
ptr= cur;
printf(“Enter Data For Node (-1):”);
scanf (“%d”,&a);
}
ptr link =Head;
}
void insert()
{
int ele;
char ch;
struct Node*ftr, *ptr,*ptr1,*cur;
ptr=Head;
ptr1=Head;
cur=(struct Node *) malloc (size of (struct Nodes);
printf(“Enter data:”);
scanf(“%d”,&cur àdata);
cur link =NULL;
printf(“Do you want to insert first(y\n):”);
flush(stdin);
scanf(“%c”,&ch);
if((ch==’y’) || (ch==’y’))
{
while(ptr link!=Head)
{
ptr=ptr link;
}
cur link =Head;
Head= cur;
ptr à link =Head;
}
else
{
printf(“After which element you want to insert:”);
scanf(“%d”,&ele);
do
{
if( ptr1 data == ele)
{
cur link =ptr1 link;
ptr1 link =cur;
}
ptr1 = ptr1 link;
}
while(ptr1!=Head);
}
}
void deletion()
{
int ele;
char ch;
struct Node *temp,*ptr,*ptr1;
ptr=ptr1=Head;
fflush(stdin);
printf(“Do you want to delete first(y\n):”);
scanf(“%c”,&ch);
if((ch==’y’)|| (ch==’y’))
{
while(ptr link!=Head)
{
ptr= ptr link;
}
cur link =Head;
Head= cur;
ptr link =Head;
}
else
{
printf(“After which element you want to insert:”);
scanf(“%d”,&ele);
do
{
if(ptr1 data ==ele)
{
cur link=ptr1 link;
ptr1 link =cur;
}
ptr1 =ptr1 àlink;
}
while(ptr1!=Head);
}
}
void deletion()
{
int ele;
char ch;
struct Node *temp,*ptr,*ptr1;
ptr=ptr1=Head;
fflush(stdin);
printf(“Do you want to delete first (y/n):”);
scanf(“%c”,&ch);
if((ch==’y’) || (ch==’y’))
{
while(ptr link!=Head)
{
ptr = ptr link;
}
Head =ptr1 link;
ptr link =Head;
free(ptr1);
}
printf(“Which element you want to delete:”);
scanf(“%d”,&ele);
do
{
if(ptr1 link data == ele)
{
temp=ptr1 link;
ptr1 link = ptr1 link link;
free(temp);
break;
}
else
{
}
while(ptr1!=Head)
}
}
void display()
{
struct Node * temp;
temp=Head;
do
{
printf(“%d” ,temp data);
temp=temp link;
}
while(temp!= Head);
}
}
void main()
{
int op;
clrscr();
create();
printf(“1.INSERTION \n”);
printf(“2.DELETION \n”);
printf(“3.DISPLAY \n”);
printf(“4.EXIT \n”);
do
{
printf(“Enter your option:\n”);
scanf(“%d”,&op);
switch (op)
{
{
case1: insertion (); break;
case2: deletion (); break;
case3: Display(); break;
case4: exit(0);
}
}
while (op<=4);
}