Question
A club compares this season's roster with last season's to announce arrivals and departures together. Given `last_year` and `this_year`, two lists of player names (no duplicates within a list), return every name that appears in exactly ONE of the two lists, sorted alphabetically. Example: last_year ["ava", "raj", "mia"] and this_year ["raj", "zoe"] give ["ava", "mia", "zoe"].
roster_changes(last_year: list[str], this_year: list[str]) → list[str][["ava","raj","mia"],["raj","zoe"]]out["ava","mia","zoe"]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.