Start by clearly defining the recursive function's contract: given a head node, return the new head of the reversed list. Then walk through the base case and the recursive step, emphasizing how the current node's next pointer is updated after the recursive call returns. Finally, discuss time and space complexity, and mention iterative alternatives for comparison.
Pro tip: Explicitly state that recursion uses O(n) stack space, which can cause stack overflow for large lists—showing awareness of production constraints at a company like Walmart, where scalability matters. Also, offer to write the code iteratively to avoid this, demonstrating versatility.
Confirm assumptions: singly linked list, reverse in-place, return new head. Ask about edge cases like empty list or single node.
State the function signature: reverse(head) returns the new head. Explain that it processes the rest of the list first, then adjusts pointers.
Base case: if head is null or head.next is null, return head. Recursive step: recursively reverse the rest, then set head.next.next = head and head.next = null.
Walk through a small list (e.g., 1->2->3) to show how pointers change and the new head is returned up the call stack.
State O(n) time and O(n) space due to recursion stack. Mention iterative approach for O(1) space and discuss trade-offs.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.