Two Sum (Trie Approach with Unbounded Alphabet)

Problem Overview

Solve the classic Two Sum problem, then extend the solution using a Trie data structure. The Trie implementation must not assume a fixed 26-letter alphabet — the alphabet is unbounded (e.g., use a hash map for children rather than a fixed-size array). You must…

• 3 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people