Decompress an encoded string
Company: C3 AI
Role: Data Scientist
Category: Coding & Algorithms
Difficulty: Medium
Interview Round: Onsite
Given an encoded string, return its decoded (decompressed) form.
Use the following encoding rule:
- A positive integer \(k\) followed by a bracketed substring means the substring is repeated \(k\) times.
- Encodings can be nested.
Examples:
- Input: `"3[a]2[bc]"` → Output: `"aaabcbc"`
- Input: `"3[a2[c]]"` → Output: `"accaccacc"`
- Input: `"2[abc]3[cd]ef"` → Output: `"abcabccdcdcdef"`
Assume:
- The input is valid.
- Digits only appear as repeat counts.
Return the decoded string.
Quick Answer: This question evaluates string parsing and manipulation skills, focusing on handling nested encodings and repetition semantics in serialized formats. Commonly asked in Coding & Algorithms interviews for Data Scientist roles, it tests reasoning about nested structures and robustness of parsing logic, representing a practical application–level problem in the domain of string processing and parsing rather than a purely theoretical exercise.