DataStructures-and-Algorithms

Interview 01

Reverse a Linked List.

Specifications

• Read all of the following instructions carefully.
• Act as an interviewer, giving a candidate a code challenge
• Score the candidate according to the Whiteboard Rubric
• You are free to offer suggestions or guidance (and see how they respond), but don’t solve it for the candidate

Feature Tasks

• Ask the candidate to write a function to reverse a Singly Linked List.
• Avoid utilizing any of the built-in methods available in your language.
• Attempt to guide the candidate to an in-place solution (i.e. avoid creating a copy of the Linked List).
• This problem can be approached in several ways:
  • Iterating over the linked list and storing a reference to a current node, its previous node, and its next node.
    • In every iteration, after the next node is stored, the current’s node next pointer is pointed at the stored reference to the previous node.
    • This solution takes O(n) time and uses O(1) extra space.
  • A recursive solution that reverses the body of the link list before re-connecting the head.
    • This solution takes O(n) time and uses O(n) space on the call stack.
  • Creating a copy of the linked list, inserting elements at the head of the new list.
    • This solution takes O(n) time and uses O(n) space.

Structure

Familiarize yourself with the grading rubric, so you know how to score the interview.

Look for effective problem solving, efficient use of time, and effective communication with the whiteboard space available.

Every solution might look a little different, but the candidate should be able to test their solution with different inputs to verify correctness.

Assign points for each item on the Rubric, according to how well the candidate executed on that skill.

Add up all the points at the end, and record the total at the bottom of the page.

Example

Input	Output
head->{3}->{2}->{1}	head->{1}->{2}->{3}
head->{'a'}->{'b'}->{'c'}	head->{'c'}->{'b'}->{'a'}

Documentation

Record detailed notes on the rubric, to share with the candidate when the interview is complete.