circular linked list in c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
struct node {
int data;
int key;
struct node *next;
};
struct node *head = NULL;
struct node *current = NULL;
bool isEmpty() {
return head == NULL;
}
int length() {
int length = 0;
//if list is empty
if(head == NULL) {
return 0;
}
current = head->next;
while(current != head) {
length++;
current = current->next;
}
return length;
}
//insert link at the first location
void insertFirst(int key, int data) {
//create a link
struct node *link = (struct node*) malloc(sizeof(struct node));
link->key = key;
link->data = data;
if (isEmpty()) {
head = link;
head->next = head;
} else {
//point it to old first node
link->next = head;
//point first to new first node
head = link;
}
}
//delete first item
struct node * deleteFirst() {
//save reference to first link
struct node *tempLink = head;
if(head->next == head) {
head = NULL;
return tempLink;
}
//mark next to first link as first
head = head->next;
//return the deleted link
return tempLink;
}
//display the list
void printList() {
struct node *ptr = head;
printf("\n[ ");
//start from the beginning
if(head != NULL) {
while(ptr->next != ptr) {
printf("(%d,%d) ",ptr->key,ptr->data);
ptr = ptr->next;
}
}
printf(" ]");
}
void main() {
insertFirst(1,10);
insertFirst(2,20);
insertFirst(3,30);
insertFirst(4,1);
insertFirst(5,40);
insertFirst(6,56);
printf("Original List: ");
//print list
printList();
while(!isEmpty()) {
struct node *temp = deleteFirst();
printf("\nDeleted value:");
printf("(%d,%d) ",temp->key,temp->data);
}
printf("\nList after deleting all items: ");
printList();
}
4
2
#include <iostream>
using namespace std;
#define NULL 0
struct node
{
int data ;
struct node *next ;
} ;
struct node *first=NULL ;
struct node *last=NULL ;
void create()
{
int i , n ;
struct node *pnode , *p ;
printf("Enter the number of nodes required:\n") ;
scanf("%d",&n) ;
printf("Enter the data value of each node:\n") ;
for(i=1 ; i<=n ; i++)
{
pnode=(struct node*)malloc(sizeof(struct node)) ;
if(pnode==NULL)
{
printf("Memory overflow. Unable to create.\n") ;
return ;
}
scanf("%d",&pnode->data) ;
if(first==NULL)
first=last=pnode ;
else
{
last->next=pnode ;
last=pnode ; /* last keeps track of last node */
}
last->next=first ;
}
}
/* This function will delete a node with value k from the Linked List if such a node exists */
void deletenode(int k)
{
struct node *p , *follow ;
/* searching the required node */
p=first ;
follow=NULL ;
while(follow!=last)
{
if(p->data==k)
break ;
follow=p ;
p=p->next ;
}
if(follow==last)
printf("Required node not found.\n") ;
else
{
if(p==first&&p==last) /* deleting the one and the only node */
first=last=NULL ;
else if(p==first) /* deleting the first node */
{
first=first->next ;
last->next=first ;
}
else if(p==last) /* deleting the last node */
{
last=follow ;
last->next=first ;
}
else /* deleting any other node */
follow->next=p->next ;
free(p) ;
}
}
/* This function will go through all the nodes of Linked List exactly once and will display data value of each node */
void traverse()
{
struct node *p , *follow ;
if(first==NULL)
printf("Circularly Linked List Empty") ;
else
{
printf("Circularly Linked List is as shown: \n") ;
p=first ;
follow = NULL ;
while(follow!=last)
{
printf("%d " , p->data) ;
follow=p ;
p=p->next ;
}
printf("\n") ;
}
}
int main()
{
int x , k , ch ;
do
{
printf("\n Menu: \n") ;
printf("1:Create Linked List \n") ;
printf("2:Delete Node \n") ;
printf("3:Traverse \n") ;
printf("4:Exit \n") ;
printf("\nEnter your choice: ") ;
scanf("%d",&ch) ;
switch(ch)
{
case 1:
create() ;
break ;
case 2:
printf("Enter the data value of the node to be deleted: ") ;
scanf("%d",&k) ;
deletenode(k) ;
break ;
case 3:
traverse() ;
break ;
case 4:
break ;
}
}
while(ch!=4) ;
return 0;
}
Thank you!
2
0
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