Code Room
CodingMedium
Question
Given a string of digits 2-9, return all letter strings the number could spell on a classic phone keypad (2->abc, 3->def, ..., 9->wxyz). Return the list sorted lexicographically; an empty input yields an empty list. The input has at most 6 digits.
Implement
letter_combinations(digits: str) → list[str]Examples
in
["23"]out["ad","ae","af","bd","be","bf","cd","ce","cf"]What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
Learn the concepts
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.
Run or narrate your approach, then ask the coach.