Code Room
CodingMedium
Question
You are given a string s of uppercase English letters and an integer k. You may replace at most k characters in s with any uppercase letter. Return the length of the longest substring that can be made to consist of a single repeated letter after performing at most k replacements. Here 1 <= len(s) <= 10^5 and 0 <= k <= len(s).
Implement
character_replacement(s: str, k: int) → intExamples
in
["ABAB",2]out4What 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.