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LeetCode 981, Medium. Topics: Hash Table, String, Binary Search, Design. View on LeetCode. Generate this problem as a practice environment: tested reference solution, 12 parametrized pytest cases, and a playground notebook:

Problem

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 "".

Examples

Explanation:

Constraints

  • 1 <= key.length, value.length <= 100
  • key and value consist of lowercase English letters and digits.
  • 1 <= timestamp <= 10^7
  • All the timestamps timestamp of set are strictly increasing.
  • At most 2 * 10^5 calls will be made to set and get.

Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

Complexity

Tags

Grind 75, Grind, NeetCode 150, NeetCode 250, NeetCode All.
Last modified on August 25, 2026