How do you insert a new node in an existing circular linked list explain with diagram?

struct Node *addToEmpty[struct Node *last, int data]

{

// This function is only for empty list

if [last != NULL]

return last;

// Creating a node dynamically.

struct Node *temp =

[struct Node*]malloc[sizeof[struct Node]];

// Assigning the data.

temp -> data = data;

last = temp;

// Note : list was empty. We link single node

// to itself.

temp -> next = last;

return last;

}

static Node addToEmpty[Node last, int data]

{

// This function is only for empty list

if [last != null]

return last;

// Creating a node dynamically.

Node temp = new Node[];

// Assigning the data.

temp.data = data;

last = temp;

// Note : list was empty. We link single node

// to itself.

temp.next = last;

return last;

}

// This code is contributed by gauravrajput1

# This function is only for empty list

def addToEmpty[self, data]:

if [self.last != None]:

return self.last

# Creating the newnode temp

temp = Node[data]

self.last = temp

# Creating the link

self.last.next = self.last

return self.last

# this code is contributed by shivanisinghss2110

static Node addToEmpty[Node last, int data]

{

// This function is only for empty list

if [last != null]

return last;

// Creating a node dynamically.

Node temp =

new Node[];

// Assigning the data.

temp.data = data;

last = temp;

// Note : list was empty. We link single node

// to itself.

temp.next = last;

return last;

}

// This code contributed by umadevi9616

function addToEmpty[last , data]

{

// This function is only for empty list

if [last != null]

return last;

// Creating a node dynamically.

var temp = new Node[];

// Assigning the data.

temp.data = data;

last = temp;

// Note : list was empty. We link single node

// to itself.

temp.next = last;

return last;

}

// This code contributed by umadevi9616

struct Node *addBegin[struct Node *last, int data]

{

if [last == NULL]

return addToEmpty[last, data];

// Creating a node dynamically.

struct Node *temp

= [struct Node *]malloc[sizeof[struct Node]];

// Assigning the data.

temp -> data = data;

// Adjusting the links.

temp -> next = last -> next;

last -> next = temp;

return last;

}

static Node addBegin[Node last, int data]

{

if [last == null]

return addToEmpty[last, data];

// Creating a node dynamically

Node temp = new Node[];

// Assigning the data

temp.data = data;

// Adjusting the links

temp.next = last.next;

last.next = temp;

return last;

}

// This code is contributed by rutvik_56

def addBegin[self, data]:

if [self.last == None]:

return self.addToEmpty[data]

temp = Node[data]

temp.next = self.last.next

self.last.next = temp

return self.last

# this code is contributed by shivanisinghss2110

static Node addBegin[Node last, int data]

{

if [last == null]

return addToEmpty[last, data];

// Creating a node dynamically

Node temp = new Node[];

// Assigning the data

temp.data = data;

// Adjusting the links

temp.next = last.next;

last.next = temp;

return last;

}

// This code is contributed by Pratham76

function addBegin[last , data]

{

if [last == null]

return addToEmpty[last, data];

// Creating a node dynamically.

var temp = new Node[];

// Assigning the data.

temp.data = data;

// Adjusting the links.

temp.next = last.next;

last.next = temp;

return last;

}

// This code contributed by Shivani

struct Node *addEnd[struct Node *last, int data]

{

if [last == NULL]

return addToEmpty[last, data];

// Creating a node dynamically.

struct Node *temp =

[struct Node *]malloc[sizeof[struct Node]];

// Assigning the data.

temp -> data = data;

// Adjusting the links.

temp -> next = last -> next;

last -> next = temp;

last = temp;

return last;

}

static Node addEnd[Node last, int data]

{

if [last == null]

return addToEmpty[last, data];

// Creating a node dynamically.

Node temp = new Node[];

// Assigning the data.

temp.data = data;

// Adjusting the links.

temp.next = last.next;

last.next = temp;

last = temp;

return last;

}

// This code is contributed by shivanisinghss2110

def addEnd[self, data]:

if [self.last == None]:

return self.addToEmpty[data]

# Assigning the data.

temp = Node[data]

# Adjusting the links.

temp.next = self.last.next

self.last.next = temp

self.last = temp

return self.last

# This code is contributed by shivanisinghss2110

static Node addEnd[Node last, int data]

{

if [last == null]

return addToEmpty[last, data];

// Creating a node dynamically.

Node temp = new Node[];

// Assigning the data.

temp.data = data;

// Adjusting the links.

temp.next = last.next;

last.next = temp;

last = temp;

return last;

}

// This code is contributed by shivanisinghss2110

function addEnd[last, data] {

if [last == null] return addToEmpty[last, data];

var temp = new Node[];

temp.data = data;

temp.next = last.next;

last.next = temp;

last = temp;

return last;

}

// this code is contributed by shivanisinghss2110

struct Node *addAfter[struct Node *last, int data, int item]

{

if [last == NULL]

return NULL;

struct Node *temp, *p;

p = last -> next;

// Searching the item.

do

{

if [p ->data == item]

{

// Creating a node dynamically.

temp = [struct Node *]malloc[sizeof[struct Node]];

// Assigning the data.

temp -> data = data;

// Adjusting the links.

temp -> next = p -> next;

// Adding newly allocated node after p.

p -> next = temp;

// Checking for the last node.

if [p == last]

last = temp;

return last;

}

p = p -> next;

} while [p != last -> next];

cout next = last;

return last;

}

struct Node *addBegin[struct Node *last, int data]

{

if [last == NULL]

return addToEmpty[last, data];

struct Node *temp =

[struct Node *]malloc[sizeof[struct Node]];

temp -> data = data;

temp -> next = last -> next;

last -> next = temp;

return last;

}

struct Node *addEnd[struct Node *last, int data]

{

if [last == NULL]

return addToEmpty[last, data];

struct Node *temp =

[struct Node *]malloc[sizeof[struct Node]];

temp -> data = data;

temp -> next = last -> next;

last -> next = temp;

last = temp;

return last;

}

struct Node *addAfter[struct Node *last, int data, int item]

{

if [last == NULL]

return NULL;

struct Node *temp, *p;

p = last -> next;

do

{

if [p ->data == item]

{

temp = [struct Node *]malloc[sizeof[struct Node]];

temp -> data = data;

temp -> next = p -> next;

p -> next = temp;

if [p == last]

last = temp;

return last;

}

p = p -> next;

} while[p != last -> next];

cout next = NULL; } else { //getting the last node node *last = getLastNode[]; last->next = n; //making the next pointer of new node point to head n->next = head; } }

Searching for an Element in the List

In searhing we do not have to do much, we just need to traverse like we did while getting the last node, in this case we will also compare the data of the Node. If we get the Node with the same data, we will return it, otherwise we will make our pointer point the next Node, and so on.

node* CircularLinkedList :: search[int x] { node *ptr = head; while[ptr != NULL && ptr->data != x] { //until we reach the end or we find a Node with data x, we keep moving ptr = ptr->next; } return ptr; }

Deleting a Node from the List

Deleting a node can be done in many ways, like we first search the Node with data which we want to delete and then we delete it. In our approach, we will define a method which will take the data to be deleted as argument, will use the search method to locate it and will then remove the Node from the List.

To remove any Node from the list, we need to do the following :

• If the Node to be deleted is the first node, then simply set the Next pointer of the Head to point to the next element from the Node to be deleted. And update the next pointer of the Last Node as well.
• If the Node is in the middle somewhere, then find the Node before it, and make the Node before it point to the Node next to it.
• If the Node is at the end, then remove it and make the new last node point to the head.

node* CircularLinkedList :: deleteNode[int x] { //searching the Node with data x node *n = search[x]; node *ptr = head; if[ptr == NULL] { cout next = n->next; return n; } else { while[ptr->next != n] { ptr = ptr->next; } ptr->next = n->next; return n; } }

Circular Linked List In C++

The arrangement shown below is for a singly linked list.

A circular linked list can be a singly linked list or a doubly linked list. In a doubly circular linked list, the previous pointer of the first node is connected to the last node while the next pointer of the last node is connected to the first node.

Its representation is shown below.

Declaration

We can declare a node in a circular linked list as any other node as shown below:

struct Node { int data; struct Node *next; };

In order to implement the circular linked list, we maintain an external pointer “last” that points to the last node in the circular linked list. Hence last->next will point to the first node in the linked list.

By doing this we ensure that when we insert a new node at the beginning or at the end of the list, we need not traverse the entire list. This is because the last points to the last node while last->next points to the first node.

This wouldn’t have been possible if we had pointed the external pointer to the first node.

Basic Operations

The circular linked list supports insertion, deletion, and traversal of the list. We will discuss each of the operations in detail now.

Insertion

We can insert a node in a circular linked list either as a first node [empty list], in the beginning, in the end, or in between the other nodes. Let us see each of these insertion operations using a pictorial representation below.

#1] Insert in an empty list

When there are no nodes in circular list and the list is empty, the last pointer is null, then we insert a new node N by pointing the last pointer to the node N as shown above. The next pointer of N will point to the node N itself as there is only one node. Thus N becomes the first as well as last node in the list.

#2] Insert at the beginning of the list

As shown in the above representation, when we add a node at the beginning of the list, the next pointer of the last node points to the new node N thereby making it a first node.

N->next = last->next

Last->next = N

#3] Insert at the end of the list

To insert a new node at the end of the list, we follow these steps:

N-> next = last ->next;
last ->next = N
last = N

#4] Insert in between the list

Suppose we need to insert a new node N between N3 and N4, we first need to traverse the list and locate the node after which the new node is to be inserted, in this case, its N3.

After the node is located, we perform the following steps.

N -> next = N3 -> next;
N3 -> next = N

This inserts a new node N after N3.

Deletion

The deletion operation of the circular linked list involves locating the node that is to be deleted and then freeing its memory.

For this we maintain two additional pointers curr and prev and then traverse the list to locate the node. The given node to be deleted can be the first node, the last node or the node in between. Depending on the location we set the curr and prev pointers and then delete the curr node.

A pictorial representation of the deletion operation is shown below.

Traversal

Traversal is a technique of visiting each and every node. In linear linked lists like singly linked list and doubly linked lists, traversal is easy as we visit each node and stop when NULL is encountered.

However, this is not possible in a circular linked list. In a circular linked list, we start from the next of the last node which is the first node and traverse each node. We stop when we once again reach the first node.

Now we present an implementation of the circular linked list operations using C++ and Java. We have implemented insertion, deletion and traversal operations here. For a clear understanding, we have depicted the circular linked list as

Thus to the last node 50, we again attach node 10 which is the first node, thereby indicating it as a circular linked list.

#include using namespace std; struct Node { int data; struct Node *next; }; //insert a new node in an empty list struct Node *insertInEmpty[struct Node *last, int new_data] { // if last is not null then list is not empty, so return if [last != NULL] return last; // allocate memory for node struct Node *temp = new Node; // Assign the data. temp -> data = new_data; last = temp; // Create the link. last->next = last; return last; } //insert new node at the beginning of the list struct Node *insertAtBegin[struct Node *last, int new_data] { //if list is empty then add the node by calling insertInEmpty if [last == NULL] return insertInEmpty[last, new_data]; //else create a new node struct Node *temp = new Node; //set new data to node temp -> data = new_data; temp -> next = last -> next; last -> next = temp; return last; } //insert new node at the end of the list struct Node *insertAtEnd[struct Node *last, int new_data] { //if list is empty then add the node by calling insertInEmpty if [last == NULL] return insertInEmpty[last, new_data]; //else create a new node struct Node *temp = new Node; //assign data to new node temp -> data = new_data; temp -> next = last -> next; last -> next = temp; last = temp; return last; } //insert a new node in between the nodes struct Node *insertAfter[struct Node *last, int new_data, int after_item] { //return null if list is empty if [last == NULL] return NULL; struct Node *temp, *p; p = last -> next; do { if [p ->data == after_item] { temp = new Node; temp -> data = new_data; temp -> next = p -> next; p -> next = temp; if [p == last] last = temp; return last; } p = p -> next; } while[p != last -> next]; cout next=[*head]->next; free[*head]; *head=last->next; } // end of list is reached or node to be deleted not there in the list while[last->next!=*head&&last->next->data!=key] { last=last->next; } // node to be deleted is found, so free the memory and display the list if[last->next->data==key] { d=last->next; last->next=d->next; cout