Question
Implement Vigenere cipher encryption. Given plaintext `text` and a `key` of letters, shift each alphabetic character of the text by the position of the corresponding key letter (a=0, b=1, ..., z=25), cycling through the key. Preserve the case of each text character. Non-alphabetic characters pass through unchanged and must NOT advance the key position. The key is non-empty and contains only ASCII letters.
vigenere_encrypt(text: str, key: str) → str["HELLO","KEY"]out"RIJVS"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.