The provided code implements a **recursive function** to insert a...

The provided code implements a recursive function to insert a new node with a specified element (elem) into a linked list at a given position (pos). Here's a breakdown of its behavior:

Function Behavior:

• Function Signature:

  Node<Integer> insertRec(Node<Integer> head, int pos, int elem)
  

  • head: The head of the linked list (or the current node being processed in the recursion).
  • pos: The position (0-based index) where the new element (elem) should be inserted.
  • elem: The value to be inserted into the linked list.
  • Return Value: The (possibly updated) head of the linked list after insertion.

Steps and Logic:

1. Base Case for Insertion (if (pos == 0)):

   • If pos == 0, the function has reached the position where the new node should be inserted.
   • A new node is created with the value elem:

     Node<Integer> newNode = new Node<>(elem);
     

   • The new node's next pointer is assigned to the current head of the list:

     newNode.next = head;
     

   • The new node is returned as the updated head of the list.

2. Base Case for End of List (if (head == null)):

   • If head == null (the end of the list has been reached), the function simply returns head. This handles the case where pos is greater than the length of the list (invalid input), and no insertion occurs.

3. Recursive Step:

   • If neither base case is met, the function recurs to the next node in the list (head.next), decrementing pos by 1:

     head.next = insertRec(head.next, pos - 1, elem);
     

   • After the recursive call, head.next is updated with the result of the recursive insertion.

4. Return Updated List:

   • After processing, the current head is returned, maintaining the structure of the resulting list.

Issues in Code:

The code you provided contains a syntax issue: the if (pos == 0) block is missing a closing brace (}). As a result, it would not compile. Here's the corrected version:

function Node<Integer> insertRec(Node<Integer> head, int pos, int elem){
  // Base case
  if(pos == 0){
    Node<Integer> newNode = new Node<>(elem);
    newNode.next = head;
    return newNode;
  }
  if(head == null) return head;
  head.next = insertRec(head.next, pos - 1, elem);
  return head;
}

Example:

Suppose the linked list is: 1 -> 2 -> 4 (head points to 1), and we call:

head = insertRec(head, 2, 3);

• Iteration 1: pos = 2

  • Moves to head.next, decrements pos to 1.

• Iteration 2: pos = 1

  • Moves to head.next, decrements pos to 0.

• Iteration 3: pos = 0

  • Creates a new node with value 3 and links it such that 2 -> 3 -> 4.

Resulting linked list: 1 -> 2 -> 3 -> 4.

Summary:

This recursive function inserts an element at the specified position in a singly linked list.