Question
You may only PREPEND characters to the front of s. Return the shortest palindrome obtainable this way. For example "aacecaaa" becomes "aaacecaaa" and "abcd" becomes "dcbabcd". An already-palindromic string is returned unchanged, and the empty string returns the empty string. Strings can be up to 10^5 characters, so an O(n) approach using the KMP failure function on s + sentinel + reverse(s) is intended.
shortest_palindrome(s: str) → str["aacecaaa"]out"aaacecaaa"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.