Circular linked list in Data Structures

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:

1. 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); }