todays-java.java

class Node {
    int data;
    Node next;

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

public class ReverseLinkedList {
    public static Node reverse(Node head) {
        Node prev = null;
        Node current = head;
        Node next = null;
        while (current != null) {
            next = current.next;
            current.next = prev;
            prev = current;
            current = next;
        }
        head = prev;
        return head;
    }

    public static void printList(Node node) {
        while (node != null) {
            System.out.print(node.data + " ");
            node = node.next;
        }
    }

    public static void main(String[] args) {
        Node head = new Node(1);
        head.next = new Node(2);
        head.next.next = new Node(3);
        head.next.next.next = new Node(4);

        System.out.println("Original linked list:");
        printList(head);
        System.out.println();

        head = reverse(head);

        System.out.println("Reversed linked list:");
        printList(head);
    }
}