0981.time-based-key-value-store

981. Time Based Key-Value Store

Create a time-based key-value store class TimeMap, that supports two operations.

1. set(string key, string value, int timestamp)
   • Stores the key and value, along with the given timestamp.
2. get(string key, int timestamp)
   • Returns a value such that set(key, value, timestamp_prev) was called previously, with timestamp_prev <= timestamp.
   • If there are multiple such values, it returns the one with the largest timestamp_prev.
   • If there are no values, it returns the empty string ("").

Example 1:

Input: inputs = ["TimeMap","set","get","get","set","get","get"], inputs = [[],["foo","bar",1],["foo",1],["foo",3],["foo","bar2",4],["foo",4],["foo",5]]
Output: [null,null,"bar","bar",null,"bar2","bar2"]
Explanation:
TimeMap kv;
kv.set("foo", "bar", 1); // store the key "foo" and value "bar" along with timestamp = 1
kv.get("foo", 1);  // output "bar"
kv.get("foo", 3); // output "bar" since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 ie "bar"
kv.set("foo", "bar2", 4);
kv.get("foo", 4); // output "bar2"
kv.get("foo", 5); //output "bar2"

Example 2:

Input: inputs = ["TimeMap","set","set","get","get","get","get","get"], inputs = [[],["love","high",10],["love","low",20],["love",5],["love",10],["love",15],["love",20],["love",25]]
Output: [null,null,null,"","high","high","low","low"]

Note:

• All key/value strings are lowercase.
• All key/value strings have length in the range [1, 100]
• The timestamps for all TimeMap.set operations are strictly increasing.
• 1 <= timestamp <= 10^7
• TimeMap.set and TimeMap.get functions will be called a total of 120000 times (combined) per test case.