LinkedList.java

class ListNode {
    int val;
    ListNode next;

    ListNode(int val) {
        this.val = val;
        this.next = null;
    }
}

public class LinkedList {

    public static ListNode removeNthFromEnd(ListNode head, int n) {
        // Create a dummy node
        ListNode dummy = new ListNode(0);
        dummy.next = head;

        // Initialize two pointers
        ListNode first = dummy;
        ListNode second = dummy;

        // Move first pointer n+1 steps ahead
        for (int i = 0; i <= n; i++) {
            first = first.next;
        }

        // Move both pointers until first reaches the end
        while (first != null) {
            first = first.next;
            second = second.next;
        }

        // Remove the nth node from the end
        second.next = second.next.next;

        // Return the modified list
        return dummy.next;
    }

    // Helper function to print the linked list
    public static void printList(ListNode head) {
        while (head != null) {
            System.out.print(head.val + " ");
            head = head.next;
        }
        System.out.println();
    }

    public static void main(String[] args) {
        // Create a linked list: 1 -> 2 -> 3 -> 4 -> 5
        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);

        // Print the original list
        System.out.print("Original List: ");
        printList(head);

        // Remove the 2nd node from the end (4 in this case)
        head = removeNthFromEnd(head, 2);

        // Print the modified list
        System.out.print("Modified List: ");
        printList(head);
    }
}