Contacted by a recruiter through LinkedIn.

Phone interview through Karat.io.

Asked 3 questions over 60 minutes. The questions were relatively simple, with few boundary cases to consider. The interviewer was looking for correctness and speed, and not focused on optimality of the solutions.

1. Check if the given grid is a valid Sudoku solution.

2. Use the given string as a substitution cipher to encode a message.

3. Given a list of random words and numeric strings, return all possible words represented by each numeric string.

Example: For words = ["AA", "A", "AB", "AC", "ABC"] and nums = [11, 12, 123], return the map:

{ 11 -> A, AA // because A can be either number 1 or 11 12 -> A, AB, AC // A is 12 OR (A is 1 and B is 2) OR .. 123 -> AB, AC, ABC // (A is 12 and B is 3) OR (A is 1, B is 2, C is 3) OR .. }