#287 · #981 · Time Based Key-Value Store(基于时间的键值存储)

Design a time-based key-value store supporting set(key, value, timestamp) and get(key, timestamp), which returns the value with the largest timestamp less than or equal to the given one, or an empty string. Timestamps for the same key are strictly increasing across set calls. Constraints: at most 2 * 10^5 calls.