0981. Time Based Key-Value Store

https://leetcode.com/problems/time-based-key-value-store

Description

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, with timestamp_prev <= timestamp. If there are multiple such values, it returns the value associated with the largest timestamp_prev. If there are no values, it returns "".

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"]
**Explanation**
TimeMap timeMap = new TimeMap();
timeMap.set("foo", "bar", 1);  // store the key "foo" and value "bar" along with timestamp = 1.
timeMap.get("foo", 1);         // return "bar"
timeMap.get("foo", 3);         // return "bar", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
timeMap.set("foo", "bar2", 4); // store the key "foo" and value "ba2r" along with timestamp = 4.
timeMap.get("foo", 4);         // return "bar2"
timeMap.get("foo", 5);         // return "bar2"

Constraints:

  • 1 <= key.length, value.length <= 100

  • key and value consist of lowercase English letters and digits.

  • 1 <= timestamp <= 107

  • All the timestamps timestamp of set are strictly increasing.

  • At most 2 * 105 calls will be made to set and get.

ac

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