Implement string reduction and time map

In a coding interview, you are asked to solve two algorithm problems. 1. **String reduction with adjacent duplicates** - Basic version: Given a string `s`, repeatedly remove any adjacent pair of equal characters until no such pair remains. Return the final string. - Follow-up: Given a string `s` and an integer `k`, repeatedly remove any group of `k` adjacent equal characters until no more removals are possible. Return the final string. - Example follow-up: if `s = "deeedbbcccbdaa"` and `k = 3`, the answer is `"aa"`. 2. **Time-based key-value store** - Design a data structure that supports: - `set(key, value, timestamp)`: store a value for a key at a given timestamp. - `get(key, timestamp)`: return the value associated with the largest timestamp less than or equal to the given timestamp for that key. If no such timestamp exists, return an empty string. - Assume timestamps passed to `set` are strictly increasing for each key. - Implement both operations efficiently. Write working code for both problems and explain the time and space complexity of your approach.