Example 1:
Input: ["TimeMap","set","get","get","set","get","get"]
[[],["foo","bar",1],["foo",1],["foo",3],["foo","bar2",4],["foo",4],["foo",5]]
Output: [null,null,"bar","bar",null,"bar2","bar2"]
Design a time-based key-value data structure that supports storing multiple values for the same key at different timestamps.
set(key, value, timestamp) stores the key-value pair, and get(key, timestamp) returns the value associated with the largest timestamp less than or equal to timestamp, or an empty string if none exists.
1 <= key.length, value.length <= 1001 <= timestamp <= 10^7set calls.Reported as LeetCode 981 in a software engineer onsite round.