Package g0901_1000.s0981_time_based_key_value_store

Class TimeMap

java.lang.Object
g0901_1000.s0981_time_based_key_value_store.TimeMap
public class TimeMap extends java.lang.Object
981 - Time Based Key-Value Store.

Medium

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 "bar2" 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.

  • Constructor Summary

    Constructors
    Constructor
    Description
    TimeMap()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    java.lang.String
    get(java.lang.String key, int timestamp)
     
    void
    set(java.lang.String key, java.lang.String value, int timestamp)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • TimeMap

      public TimeMap()

  • Method Details

    • set

      public void set(java.lang.String key, java.lang.String value, int timestamp)

    • get

      public java.lang.String get(java.lang.String key, int timestamp)