Insertion at specific position in Circular Linked List in C++

Insertion at specific position in circular linked list

How we can insert data at specific position in circular linked list?

Insertion at specific position in circular linked list in C++ is one the insertion operation that we can perform on the circular linked list. In this article we will be learning steps and algorithm to do the same. We can perform insertion at following places also:-

  • Insertion at the beginning of the circular linked list.
  • Insertion at the end of the circular linked list.

Steps to insert new node at specific position in circular linked list in CPP

  1. If the circular linked list is empty, terminate function.
  2. Else define two node pointers.
  3. Create new node and stor the data in the new node
  4. Now traverse till the specific position and insert this new node there.
  5. Link the pointer of this new node to the node present at this place previously.
  6. Print the new circular linked list to see the result.

Syntax

class Node  

    int data; 
    Node *next; 
}; 
Insertion at specific position in circular linked list in C++

Algorithm to write a CPP program to insert at specific position in Circular Linked List

  • STRUCT NEWNODE & CURNODE
  • IF HEAD==NULL
  • EXIT
  • ELSE
  • NEWNODE->NUM=NUM
  • CURNODE=HEAD
  • FOR I=0 TO POS-3
  • CURRNODE=CURRNODE->NEXT
  • END FOR
  • NEWNODE->NEXT=CURNODE->NEXT
  • CURNODE->NEXT=NEWNODE

C++ program for insertion at specific position in circular linked list

Run
#include<iostream>
using namespace std;

struct Node
{
  int num;
  struct Node *next;
} *head;

void insertStart (struct Node **head, int data)	//function to create linked list
{
  struct Node *newNode = (struct Node *) malloc (sizeof (struct Node));
  newNode->num = data;

  // if its the first node being entered
  if (*head == NULL)
    {
      *head = newNode;		// assigning itself as head
      (*head)->next = *head;	// assigning itself as next node

      cout << newNode->num << " Inserted\n";
      return;
    }

  // if CLL already as >=1 node
  struct Node *curr = *head;

  // traverse till last node in CLL
  while (curr->next != *head)
    {
      curr = curr->next;
    }

  curr->next = newNode;		// last node's next as this new node
  newNode->next = *head;	// new node's next as current head node

  *head = newNode;		// changing head node to this new node
  cout << newNode->num << " Inserted\n";

  // previous head node becomes 2nd node
}

void insertSpecific(struct Node **head,int num, int pos)//function to insert element at specific position
{
    struct Node *newnode, *curNode;
    int i;

    if(*head == NULL)
    {
        cout<<"List is empty";
    }
    else
    {
        newnode = (struct Node *)malloc(sizeof(struct Node));
        newnode->num = num;
        curNode = *head;
        for(i=0; i<=pos-3; i++) { curNode = curNode->next;
        }
        newnode->next = curNode->next;
        curNode->next = newnode;
    }
} 
void display (struct Node *head)
{

  cout << "\nCircular Linked List : " << endl;

  // if circular linked list is empty currently
  if (head == NULL)
    return;

  struct Node *temp = head;

  // since we need to take care of circular nature of linked list
  do
    {
      cout << temp->num << " ";
      temp = temp->next;

    }
  while (temp != head);
  cout << endl;
}

int main ()				//main function
{
  // first node will be null at creation    
  struct Node *head = NULL;

  insertStart (&head, 1);
  insertStart (&head, 2);
  insertStart (&head, 3);
  insertStart (&head, 4);
  insertStart (&head, 5);
  cout<<"Before insertion ";
  display (head);
  insertSpecific (&head,8,2);
  cout<<"After insertion ";
  display (head);
  return 0;
}
Output:

1 Inserted
2 Inserted
3 Inserted
4 Inserted
5 Inserted
Before insertion 
Circular Linked List : 
5 4 3 2 1 
After insertion 
Circular Linked List : 
5 8 4 3 2 1 

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