CodingMediumcod-g618

Subject StringsLevel Mid–Senior~26 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a string s of lowercase letters, remove duplicate letters so that every letter appears exactly once and the result is the lexicographically smallest string among all such results (preserving relative order of the kept letters). 1 <= len(s) <= 10000. Example: 'cbacdcbc' -> 'acdb'.

Implement

remove_duplicate_letters(s: str) → str

Examples

in["cbacdcbc"]out"acdb"

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.