diff --git a/README.md b/README.md
index afb3302e..6444e9be 100644
--- a/README.md
+++ b/README.md
@@ -650,6 +650,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 967. Numbers With Same Consecutive Differences                   | [Link](https://leetcode.com/problems/numbers-with-same-consecutive-differences/)                   | [Link](./lib/medium/967_numbers_with_same_consecutive_differences.rb)                   | [Link](./test/medium/test_967_numbers_with_same_consecutive_differences.rb)                   |
 | 973. K Closest Points to Origin                                  | [Link](https://leetcode.com/problems/k-closest-points-to-origin/)                                  | [Link](./lib/medium/973_k_closest_points_to_origin.rb)                                  | [Link](./test/medium/test_973_k_closest_points_to_origin.rb)                                  |
 | 979. Distribute Coins in Binary Tree                             | [Link](https://leetcode.com/problems/distribute-coins-in-binary-tree/)                             | [Link](./lib/medium/979_distribute_coins_in_binary_tree.rb)                             | [Link](./test/medium/test_979_distribute_coins_in_binary_tree.rb)                             |
+| 981. Time Based Key-Value Store                                  | [Link](https://leetcode.com/problems/time-based-key-value-store/)                                  | [Link](./lib/medium/981_time_based_key_value_store.rb)                                  | [Link](./test/medium/test_981_time_based_key_value_store.rb)                                  |
 | 1400. Construct K Palindrome Strings                             | [Link](https://leetcode.com/problems/construct-k-palindrome-strings/)                              | [Link](./lib/medium/1400_construct_k_palindrome_strings.rb)                             | [Link](./test/medium/test_1400_construct_k_palindrome_strings.rb)                             |
 | 2116. Check if a Parentheses String Can Be Valid                 | [Link](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/)                  | [Link](./lib/medium/2116_check_if_a_parentheses_string_can_be_valid.rb)                 | [Link](./test/medium/test_2116_check_if_a_parentheses_string_can_be_valid.rb)                 |
 | 2425. Bitwise XOR of All Pairings                                | [Link](https://leetcode.com/problems/bitwise-xor-of-all-pairings/)                                 | [Link](./lib/medium/2425_bitwise_xor_of_all_pairings.rb)                                | [Link](./test/medium/test_2425_bitwise_xor_of_all_pairings.rb)                                |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index a507e12e..89626899 100644
--- a/leetcode-ruby.gemspec
+++ b/leetcode-ruby.gemspec
@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '8.1.7'
+  s.version = '8.1.8'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/981_time_based_key_value_store.rb b/lib/medium/981_time_based_key_value_store.rb
new file mode 100644
index 00000000..f07bada9
--- /dev/null
+++ b/lib/medium/981_time_based_key_value_store.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/time-based-key-value-store/
+class TimeMap
+  # Init
+  def initialize
+    @keys = {}
+  end
+
+  # @param {String} key
+  # @param {String} value
+  # @param {Integer} timestamp
+  # @return {Void}
+  def set(key, value, timestamp)
+    @keys[key] ||= []
+    @keys[key] << [timestamp, value]
+  end
+
+  # @param {String} key
+  # @param {Integer} timestamp
+  # @return {Void}
+  def get(key, timestamp)
+    return '' unless @keys.key?(key) && timestamp >= @keys[key].first[0]
+
+    l = 0
+    r = @keys[key].size
+
+    while l < r
+      m = (l + r) / 2
+
+      if @keys[key][m][0] <= timestamp
+        l = m + 1
+      else
+        r = m
+      end
+    end
+
+    r.zero? ? '' : @keys[key][r - 1][1]
+  end
+end
diff --git a/test/medium/test_981_time_based_key_value_store.rb b/test/medium/test_981_time_based_key_value_store.rb
new file mode 100644
index 00000000..b2ed231f
--- /dev/null
+++ b/test/medium/test_981_time_based_key_value_store.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/981_time_based_key_value_store'
+require 'minitest/autorun'
+
+class TimeBasedKeyValueStoreTest < ::Minitest::Test
+  def test_default_one
+    time_map = ::TimeMap.new
+
+    time_map.set('foo', 'bar', 1)
+
+    assert_equal('bar', time_map.get('foo', 1))
+    assert_equal('bar', time_map.get('foo', 3))
+
+    time_map.set('foo', 'bar2', 4)
+
+    assert_equal('bar2', time_map.get('foo', 4))
+    assert_equal('bar2', time_map.get('foo', 5))
+  end
+
+  def test_additional_one
+    time_map = ::TimeMap.new
+
+    time_map.set('love', 'high', 10)
+    time_map.set('love', 'low', 20)
+
+    assert_equal('', time_map.get('love', 5))
+    assert_equal('high', time_map.get('love', 10))
+    assert_equal('high', time_map.get('love', 15))
+    assert_equal('low', time_map.get('love', 20))
+    assert_equal('low', time_map.get('love', 25))
+  end
+end