Given a Circular Linked List, the task is to add a New Node at the Middle of the List. Let’s consider the following Circular Linked List:
List-Before-Insertion
List-After-Insertion
- Create a new node (New_node).
- Check for an empty list. If the list is empty then insert the node as head.
- For non-empty list, calculate the length of the list.
- Create variable mid and store middle length in it.
- Create two nodes Temporary and Current.
- Now traverse the list till Temporary reaches the midpoint of the list using the mid variable.
- Insert the New_node after the Current.
- Make Current.next point to New node and New_node.next to Temporary.
- Node is inserted.
Below is the implementation of the above approach:
Java
// Java Program to Insert a New Node at// the Middle of the Circular Linked Listimport java.io.*;public class GFG { // Stores Information about Node of List public class Node { int data; Node next; public Node(int data) { this.data = data; } } // Declaring Head of the Node public Node head_of_node = null; // A last pointer to help append values to our list public Node last = null; // keep count of size of the list public int length_of_list; // Add method adds values to the end of the list public void add(int data) { Node newNode = new Node(data); if (head_of_node == null) { head_of_node = newNode; last = newNode; newNode.next = head_of_node; } else { last.next = newNode; last = newNode; last.next = head_of_node; } // keep count of size of list length_of_list++; } // Method to insert Node in the middle of the list public void Insert_In_Middle(int data) { // creating a new node that is to be inserted Node New_node = new Node(data); // check for empty list if (head_of_node == null) { head_of_node = New_node; last = New_node; New_node.next = head_of_node; } // If the list is not empty else { // Declaring nodes Node temporary; Node current; // Checking if the length of list // if even or odd int mid_point_check = (length_of_list % 2); // mid point for even length if (mid_point_check == 0) { length_of_list = length_of_list / 2; } // mid point for odd length else { length_of_list = (length_of_list + 1) / 2; } // temporary points to the head of list temporary = head_of_node; current = null; // loop till we reach the mid point while (length_of_list > 0) { // make current point to the previous node current = temporary; temporary = temporary.next; length_of_list -= 1; } // make the previous node point to the new node current.next = New_node; // make the new_node.next point to temporary New_node.next = temporary; } // increasing the length of list after insertion of // new node length_of_list++; } // Print_list method iterates through the list and // prints the values stored in the list public void Print_List() { Node current = head_of_node; if (head_of_node == null) { System.out.println("Your list is empty"); } else { do { System.out.print(" " + current.data); current = current.next; } while (current != head_of_node); System.out.println(); } } // Driver code public static void main(String[] args) { GFG circular_list = new GFG(); circular_list.add(10); circular_list.add(20); circular_list.add(30); circular_list.add(40); System.out.print("Original List --> "); circular_list.Print_List(); circular_list.Insert_In_Middle(60); System.out.print("List after Inserting --> "); circular_list.Print_List(); }} |
Output
Original List --> 10 20 30 40 List after Inserting --> 10 20 60 30 40
Time complexity: O(n) where n is no of nodes of circular linked list
Auxiliary space: O(1) because using constant variables
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