In the Deletion in Circular Linked List in C we can delete the node in the following ways :
Deletion from the Beginning
Deletion from the End
Deletion from the specific Position
Deletion in Circular Linked List in C
In this topic we want to discuss about delete the any node in circular linked list So, In this scenario is also have three ways to delete the node in linked list like doubly or singly linked list.
Deletion at beginning
Deletion at middle
Deletion at end
1. It is not easy to reverse the linked list. 2. If proper care is not taken, then the problem of infinite loop can occur.
3. If we are at a node, then we can go to any node. But in linear linked list it is not possible to go to previous node. Easy implementation of some operations is possible
Deletion at beginning
Let’s have a look at the code for deletion at the beginning –
void deleteBegin(struct Node **head)
{
struct Node *temp = *head;
// if there are no nodes in Linked List can't delete
if (*head == NULL)
{
printf ("Linked List Empty, nothing to delete");
return;
}
// if only 1 node in CLL
if (temp->next == *head)
{
*head = NULL;
return;
}
struct Node *curr = *head;
// traverse till last node in CLL
while (curr->next != *head)
curr = curr->next;
// assign last node's next to 2nd node in CLL
curr->next = (*head)->next;
// move head to next node
*head = (*head)->next;
free (temp);
}
Let’s have a look at the code for deletion at the end –
void deleteEnd (struct Node **head)
{
struct Node *temp = *head;
struct Node *previous;
// if there are no nodes in Linked List can't delete
if (*head == NULL)
{
printf ("Linked List Empty, nothing to delete");
return;
}
// if Linked List has only 1 node
if (temp->next == *head)
{
*head = NULL;
return;
}
// else traverse to the last node
while (temp->next != *head)
{
// store previous link node as we need to change its next val
previous = temp;
temp = temp->next;
}
// Curr assign 2nd last node's next to head
previous->next = *head;
// delete the last node
free (temp);
// 2nd last now becomes the last node
}
Deletion in between (After a given node)
Let’s have a look at the code for deletion after a given node –
void deletePos (struct Node **head, int n)
{
int size = calcSize (*head);
if (n < 1 || size < n)
{
printf ("Can't delete, %d is not a valid position\n", n);
}
else if (n == 1)
deleteFront (head);
else if (n == size)
deleteEnd (head);
else
{
struct Node *temp = *head;
struct Node *previous;
// traverse to the nth node
while (--n)
{
// store previous link node as we need to change its next val
previous = temp;
temp = temp->next;
}
// change previous node's next node to nth node's next node
previous->next = temp->next;
// delete this nth node
free (temp);
}
}
#include<stdio.h>
#include<stdlib.h>
// structure for Circular Linked List
struct Node
{
int data;
struct Node *next;
};
int calcSize (struct Node *head);
void deleteBegin(struct Node **head)
{
struct Node *tempNode = *head;
// if there are no nodes in Linked List can't delete
if (*head == NULL)
{
printf ("Linked List Empty, nothing to delete");
return;
}
// if only 1 node in CLL
if (tempNode->next == *head)
{
*head = NULL;
return;
}
struct Node *curr = *head;
// traverse till last node in CLL
while (curr->next != *head)
curr = curr->next;
// assign last node's next to 2nd node in CLL
curr->next = (*head)->next;
// move head to next node
*head = (*head)->next;
free (tempNode);
}
void deleteEnd (struct Node **head)
{
struct Node *tempNode = *head;
struct Node *previous;
// if there are no nodes in Linked List can't delete
if (*head == NULL)
{
printf ("Linked List Empty, nothing to delete");
return;
}
// if Linked List has only 1 node
if (tempNode->next == *head)
{
*head = NULL;
return;
}
// else traverse to the last node
while (tempNode->next != *head)
{
// store previous link node as we need to change its next val
previous = tempNode;
tempNode = tempNode->next;
}
// Curr assign 2nd last node's next to head
previous->next = *head;
// delete the last node
free (tempNode);
// 2nd last now becomes the last node
}
void deletePos (struct Node **head, int n)
{
int size = calcSize (*head);
if (n < 1 || size < n)
{
printf ("Can't delete, %d is not a valid position\n", n);
}
else if (n == 1)
deleteBegin(head);
else if (n == size)
deleteEnd (head);
else
{
struct Node *tempNode = *head;
struct Node *previous;
// traverse to the nth node
while (--n)
{
// store previous link node as we need to change its next val
previous = tempNode;
tempNode = tempNode->next;
}
// change previous node's next node to nth node's next node
previous->next = tempNode->next;
// delete this nth node
free (tempNode);
}
}
void insert (struct Node **head, int data)
{
struct Node *newNode = (struct Node *) malloc (sizeof (struct Node));
newNode->data = data;
if (*head == NULL)
{
*head = newNode;
(*head)->next = *head;
return;
}
struct Node *curr = *head;
while (curr->next != *head)
{
curr = curr->next;
}
curr->next = newNode;
newNode->next = *head;
*head = newNode;
}
int calcSize (struct Node *head)
{
int size = 0;
struct Node *temp = head;
if (temp == NULL)
return size;
do
{
size++;
temp = temp->next;
}
while (temp != head);
return size;
}
void display (struct Node *head)
{
// if there are no node in CLL
if (head == NULL)
return;
struct Node *temp = head;
//need to take care of circular structure of CLL
do
{
printf ("%d ", temp->data);
temp = temp->next;
}
while (temp != head);
printf ("\n");
}
int main ()
{
// first node will be null at creation
struct Node *head = NULL;
insert (&head, 10);
insert (&head, 11);
insert (&head, 12);
insert (&head, 13);
insert (&head, 14);
insert (&head, 15);
insert (&head, 16);
display (head);
deleteBegin(&head);
display (head);
deleteEnd (&head);
display (head);
deletePos (&head, 3);
display (head);
return 0;
}
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