Linked_List.java

public class Linked_List {
    public static void main(String[] args) {
        linked_list list = new linked_list();

        // Inserting at beginning
        list.insertAtBeginning(10);
        list.insertAtBeginning(20);
        list.insertAtBeginning(30);
        System.out.println("After insertAtBeginning:");
        list.display();

        //Reversal of the Linked List
        list.reversal();
        list.display();

        // Inserting at end
        list.insertAtEnd(99);
        System.out.println("\nAfter insertAtEnd:");
        list.display();

        // Inserting at position
        list.insertAtPosition(25, 2); // Should insert between 30 and 20
        System.out.println("\nAfter insertAtPosition (25 at index 2):");
        list.display();

        // Deleting from beginning
        list.deleteFromBeginning();
        System.out.println("\nAfter deleteFromBeginning:");
        list.display();

        // Deleting from end
        list.deleteFromEnd();
        System.out.println("\nAfter deleteFromEnd:");
        list.display();

        // Deleting from position
        list.deleteFromPosition(1); // Should delete node at index 1
        System.out.println("\nAfter deleteFromPosition (index 1):");
        list.display();

        // Display final size
        int size = list.list_size();
        System.out.println("\nFinal size of list: " + size);

    }

    public static class Node {
        int data;
        Node next;

        public Node(int data) {
            this.data = data;
            this.next = null;
        }
    }

    public static class linked_list {
        Node head;

        public void insertAtBeginning(int data) {
            Node created_node = new Node(data);
            created_node.next = head;
            head = created_node;
        }

        public void insertAtEnd(int data) {
            Node created_node = new Node(data);
            if (head == null) {
                return;
            }
            Node temp = head;
            while (temp.next != null) {
                temp = temp.next;
            }
            temp.next = created_node;
        }

        public void insertAtPosition(int data, int position) {
            Node created_node = new Node(data);
            Node temp = head;
            for (int i = 0; i < position; i++) {
                temp = temp.next;
            }
            created_node.next = temp.next;
            temp.next = created_node;
        }

        public void deleteFromBeginning() {
            if (head == null) {
                System.out.println("You cannot delete from an Empty Linked List");
                return;
            }
            Node temp = head;
            head = head.next;
            temp.next = null;
        }

        public void deleteFromEnd() {
            Node temp = head;
            if (temp.next == null) {
                head = null;
                return;
            }
            while (temp.next.next != null) {
                temp = temp.next;
            }
            temp.next = null;
        }

        public void deleteFromPosition(int position) {
            Node temp = head;
            if(position < 0 || head == null){
                System.out.println("Error in given position or list is empty");
                return;
            }
            if(position == 0){
                head = head.next;
                return;
            }
            for (int i = 0; i < position - 1; i++) {
                if (temp.next == null) {
                    System.out.println("Position out of bounds");
                    return;
                }
                temp = temp.next;
            }
            if (temp.next == null) {
                System.out.println("No node exists at your given position");
                return;
            }
            Node deleted = temp.next;
            temp.next = temp.next.next;
            deleted.next = null;
        }
        public void display(){
            Node temp = head;
            if(temp == null){
                System.out.println("The Linked List is empty");
                return;
            }
            do {
                System.out.print(temp.data + " -> ");
                temp = temp.next;
            } while (temp != null);
            System.out.print("null\n");
        }
        public int list_size(){
            if(head == null){
                return 0;
            }
            int counter = 0;
            Node temp = head;
            do {
                temp = temp.next;
                counter++;
            } while(temp != null);
            return counter;
        }
        public void reversal(){
            Node temp = head;
            Node prev = null;
            Node curr = temp;
            while(curr != null){
                Node next = curr.next;
                curr.next = prev;
                prev = curr;
                curr = next;
            }
            head = prev;
        }
    }
}