Question
Given a lowercase string s and a lowercase string t, return the shortest substring (window) of s that contains every character of t including multiplicity (a character needed twice must appear at least twice in the window). If no such window exists, return the empty string. If multiple shortest windows tie, return the leftmost. Lengths up to a few thousand.
min_window_substring(s: str, t: str) → str["adobecodebanc","abc"]out"banc"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.
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.