Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key's value at a certain timestamp.
Implement the TimeMap class:
TimeMap()Initializes the object of the data structure.void set(String key, String value, int timestamp)Stores the key key with the value value at the given time timestamp.String get(String key, int timestamp)Returns a value such that set was called previously, withtimestamp_prev <= timestamp. If there are multiple such values, it returns the value associated with the largesttimestamp_prev. If there are no values, it returns "".