Hey guys is there is any problem in test case. I think there is problem in the 2 4 because for that atleast we require 3 node . and if i am correct then please correct the input as soon as possible

This is NOT a properly designed test case. Output is getting swapped when linked list starts with 2. Dont waste your time on this question.

Either the test case that the author has included is broken or they have incorrectly described the test data and how the function should work. I was only able to pass it by including some special case code to get rid of a head node with data=2 and insert a tail node with a data=2. This challenge should be deleted until the author can fix the issues.

There is a flaw in the design of the problem's INPUT/OUTPUT.

• It should give head as NULL which it does not.
• There is an extra number expected at the end of the linked list

This is accepted code,

Node* InsertNth(Node *head, int data, int position)
{
    if (position == 0)
        return head = new Node({data, new Node({2, NULL})});

    Node* root = head;
    while (root->next && --position)
        root = root->next;
    root->next = new Node({data, root->next});
    return head;
}

And, this is what accepted code should look like,

Node* InsertNth(Node *head, int data, int position)
{
    if (head == NULL)
        return head = new Node({data, NULL});
    if (position == 0)
        return head = new Node({data, head->next});

    // strict checking as my habit
    if (position < 0)
        return NULL;

    Node* root = head;
    while (root->next && --position)
        root = root->next;
    root->next = new Node({data, root->next});
    return head;
}

This problem statement is pretty horrible. What exactly is the input format?