CIRCULAR SINGLE LINK LIST
#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
typedef struct node
{
int data;
struct node *next;
}node;
int main()
{
int ch,item;
node *head=NULL;
node *get_node(int );
node *creat_circular_ll(node *);
void display(node *);
node *ins_beg(node* );
node *insert_mid(node *);
node *ins_end(node* );
node *insert_after_a_given_node(node *);
node *insert_before_a_given_node(node *);
node *del_beg(node* );
node *del_mid(node *);
node *del_end(node* );
do
{
printf("-----------------------------------------------\n");
printf("| CIRCULAR LINK LIST |\n");
printf("-----------------------------------------------\n");
printf("| 1.Creat list |\n");
printf("| 2.Display list |\n");
printf("| 3.Insert beginning |\n");
printf("| 4.Insert middle |\n");
printf("| 5.Insert end |\n");
printf("| 6.Insert after a given node |\n");
printf("| 7.Insert before a given node |\n");
printf("| 8.Delete beginning |\n");
printf("| 9.Delete middle |\n");
printf("|10.Delete end |\n");
printf("|11.Exit from the program |\n");
printf("-----------------------------------------------\n");
printf("Enter your choice: ");
scanf("%d",&ch);
printf("\n");
switch(ch)
{
case 1:
head=creat_circular_ll(head);
break;
case 2:
display(head);
break;
case 3:
head=ins_beg(head);
break;
case 4:
head=insert_mid(head);
break;
case 5:
head=ins_end(head);
break;
case 6:
head=insert_after_a_given_node(head);
break;
case 7:
head=insert_before_a_given_node(head);
break;
case 8:
head=del_beg(head);
break;
case 9:
head=del_mid(head);
break;
case 10:
head=del_end(head);
break;
case 11:
exit(0);
default :
printf("Wrong choice...\n\n");
}
}while(1);
return 1;
}
node *get_node(int x)
{
node *p;
p=(node*)malloc(sizeof(node));
p->data=x;
p->next=NULL;
return p;
}
node *creat_circular_ll(node *head)
{
node *p;
int x;
char ch='y';
head=NULL;
while(1)
{
printf("If you do not want to add data then Enter (-999)\nEnter data ");
scanf("%d",&x);
if(x==-999)
break;
else
{
p=get_node(x);
if(head==NULL)
{
head=p;
p->next=head;
}
else
{
p->next=head->next;
head->next=p;
head=p;
}
}
}
return head;
}
void display(node *head)
{
node *p;
if(head==NULL)
{
printf("link list not exist.\n");
return;
}
p=head->next;
while(p!=head)
{
printf("[%d]->",p->data);
p=p->next;
}
printf("[%d] \n",p->data);
}
node *ins_beg(node* head)
{
node *p;
int x;
printf("Enter the element: ");
scanf("%d",&x);
p=get_node(x);
if(head==NULL)
{
head=p;
p->next=head;
}
else
{
p->next=head->next;
head->next=p;
}
return head;
}
node *insert_mid(node *head)
{
node *p,*q;
int x,pos,c=1;
printf("Enter the value which you wand to insert at the middle: ");
scanf("%d",&x);
printf("Enter the position where you insert the given value: ");
scanf("%d",&pos);
p=get_node(x);
if(head==NULL)
{
head=p;
p->next=p;
}
else if(pos==1)
{
p->next=head->next;
head->next=p;
}
else
{
q=head->next;
while(c<pos-1&&q!=head)
{
c++;
q=q->next;
}
if(q==head)
{
p->next=head->next;
head->next=p;
head=p;
}
else
{
p->next=q->next;
q->next=p;
}
return head;
}
}
node *ins_end(node* head)
{
node *p;
int x;
printf("Enter the element: ");
scanf("%d",&x);
p=get_node(x);
if(head==NULL)
{
head=p;
p->next=p;
}
else
{
p->next=head->next;
head->next=p;
head=p;
}
return head;
}
node *insert_after_a_given_node(node *head)
{
node *p,*q;
int x,y;
if(head==NULL)
{
printf("link list not exist.\n");
return head;
}
printf("Enter the value which you wand to insert: ");
scanf("%d",&x);
printf("Enter the value after you want to insert: ");
scanf("%d",&y);
q=head->next;
p=get_node(x);
while(q->data!=y&&q!=head)
{
q=q->next;
}
if(q->data!=y)
{
printf("Entered data %d not found\n",y);
return head;
}
p->next=q->next;
q->next=p;
if(q==head)
head=head->next;
return head;
}
node *insert_before_a_given_node(node* head)
{
node *p,*q,*r;
int x,y;
if(head==NULL)
{
printf("link list not exist.\n");
return head;
}
printf("Enter the value which you wand to insert: ");
scanf("%d",&x);
printf("Enter the value of the node before you want to insert: ");
scanf("%d",&y);
q=head->next;
r=head->next;
p=get_node(x);
if(q->data==y)
{
p->next=head->next;
head->next=p;
return head;
}
while(r->data!=y&&r!=head)
{
q=r;
r=r->next;
}
if(r->data!=y)
{
printf("Entered data not found\n");
return;
}
p->next=q->next;
q->next=p;
return head;
}
node *del_beg(node* head)
{
node *p;
if(head==NULL)
{
printf("Deletion from the begging can not be done bcz link list not exist.\n");
return head;
}
p=head->next;
if(head==p)
head=NULL;
else
head->next=p->next;
free(p);
return head;
}
node *del_end(node* head)
{
node *p,*q;
if(head==NULL)
{
printf("Deletion from the end can not be done bcz link list not exist.\n");
return head;
}
p=head->next;
while(p->next!=head)
p=p->next;
if(head==p)
head=NULL;
else
{
p->next=head->next;
q=head;
head=p;
p=q;
}
free(p);
return head;
}
node *del_mid(node *head)
{
node *p,*q;
int x;
if(head==NULL)
{
printf("link list not exist.\n");
return head;
}
printf("Enter the element which you want to delete: ");
scanf("%d",&x);
p=head->next;
q=head->next;
while(q!=head&&q->data!=x)
{
p=q;
q=q->next;
}
if(q->data!=x)
{
printf("Element not founf so deletion can not be done\n");
return head;
}
if(p==q)
{
if(p==head)
head=NULL;
else
head->next=p->next;
}
else if(q==head)
{
head=p;
head->next=q->next;
}
else
p->next=q->next;
free(q);
return head;
}