basics using linked list

 

Operation Using Linked List in Data Structure: Traversal, Insertion, Deletion and Searching 


import java.util.Scanner;

// Node class represents each element in the linked list
class Node {
    int data;
    Node next;

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

// Custom LinkedList class to manage linked list operations
class LinkedList {
    private Node head;

    // Function to insert an element at the end of the linked list
    public void insert(int data) {
        Node newNode = new Node(data);
        if (head == null) {
            head = newNode;
        } else {
            Node current = head;
            while (current.next != null) {
                current = current.next;
            }
            current.next = newNode;
        }
    }

    // Function to insert an element at a specific index in the linked list
    public void insertAtIndex(int data, int index) {
        Node newNode = new Node(data);
        if (index < 0) {
            System.out.println("Invalid index. Insertion failed.");
            return;
        }
        if (index == 0) {
            // Insert at the beginning
            newNode.next = head;
            head = newNode;
        } else {
            // Insert at a specific index
            Node current = head;
            int currentIndex = 0;
            while (current != null && currentIndex < index - 1) {
                current = current.next;
                currentIndex++;
            }
            if (current == null) {
                System.out.println("Invalid index. Insertion failed.");
                return;
            }
            newNode.next = current.next;
            current.next = newNode;
        }
    }

    // Function to traverse and print the linked list
    public void traverse() {
        Node current = head;
        System.out.println("Traversal:");
        while (current != null) {
            System.out.print(current.data + " ");
            current = current.next;
        }
        System.out.println();
    }

    // Function to delete an element from the linked list
    public void delete(int data) {
        if (head == null) {
            System.out.println("The list is empty. Deletion failed.");
            return;
        }

        if (head.data == data) {
            head = head.next;
            System.out.println("Element " + data + " deleted.");
            return;
        }

        Node current = head;
        Node prev = null;

        while (current != null && current.data != data) {
            prev = current;
            current = current.next;
        }

        if (current == null) {
            System.out.println("Element " + data + " not found. Deletion failed.");
        } else {
            prev.next = current.next;
            System.out.println("Element " + data + " deleted.");
        }
    }

    // Function to search for an element in the linked list
    public boolean search(int data) {
        Node current = head;
        while (current != null) {
            if (current.data == data) {
                return true;
            }
            current = current.next;
        }
        return false;
    }
}

// Main class to interactively perform linked list operations
class LinkedListOperations {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        LinkedList linkedList = new LinkedList();

        while (true) {
            System.out.println("Select an operation:");
            System.out.println("1. Traversal");
            System.out.println("2. Insertion at the end");
            System.out.println("3. Insertion at a specific index");
            System.out.println("4. Deletion");
            System.out.println("5. Searching");
            System.out.println("6. Exit");
            System.out.print("Enter your choice: ");
            int choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    linkedList.traverse();
                    break;

                case 2:
                    System.out.print("Enter the value to insert at the end: ");
                    int valueToInsert = scanner.nextInt();
                    linkedList.insert(valueToInsert);
                    break;

                case 3:
                    System.out.print("Enter the value to insert: ");
                    int value = scanner.nextInt();
                    System.out.print("Enter the index to insert at: ");
                    int index = scanner.nextInt();
                    linkedList.insertAtIndex(value, index);
                    break;

                case 4:
                    System.out.print("Enter the element to delete: ");
                    int elementToDelete = scanner.nextInt();
                    linkedList.delete(elementToDelete);
                    break;

                case 5:
                    System.out.print("Enter the element to search for: ");
                    int target = scanner.nextInt();
                    boolean found = linkedList.search(target);
                    if (found) {
                        System.out.println("Element " + target + " found.");
                    } else {
                        System.out.println("Element " + target + " not found.");
                    }
                    break;

                case 6:
                    System.out.println("Exiting program.");
                    scanner.close();
                    System.exit(0);

                default:
                    System.out.println("Invalid choice. Please try again.");
                    break;
            }
        }
    }
}

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