Question
Decode a string encoded with the rule k[encoded_string], where the bracketed substring is repeated exactly k times. k is a positive integer and encoding may be nested. The input contains only lowercase letters, digits, and brackets, is always well-formed, has length 1 to 10^4, and the decoded output fits comfortably in memory (under ~10^5 characters). Return the decoded string.
decode_string(s: str) → str["3[a]2[bc]"]out"aaabcbc"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.