Remove duplicate letters
Your task
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'.
Examples
remove_duplicate_letters(s: str) -> strExample 1
Input
remove_duplicate_letters("cbacdcbc")Output
"acdb"