diff --git a/README.md b/README.md
index 07e91274..f00fcfc4 100644
--- a/README.md
+++ b/README.md
@@ -740,6 +740,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 2130. Maximum Twin Sum of a Linked List                                             | [Link](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list/)                                             | [Link](./lib/medium/2130_maximum_twin_sum_of_a_linked_list.rb)                                             | [Link](./test/medium/test_2130_maximum_twin_sum_of_a_linked_list.rb)                                             |
 | 2131. Longest Palindrome by Concatenating Two Letter Words                          | [Link](https://leetcode.com/problems/longest-palindrome-by-concatenating-two-letter-words/)                          | [Link](./lib/medium/2131_longest_palindrome_by_concatenating_two_letter_words.rb)                          | [Link](./test/medium/test_2131_longest_palindrome_by_concatenating_two_letter_words.rb)                          |
 | 2149. Rearrange Array Elements by Sign                                              | [Link](https://leetcode.com/problems/rearrange-array-elements-by-sign/)                                              | [Link](./lib/medium/2149_rearrange_array_elements_by_sign.rb)                                              | [Link](./test/medium/test_2149_rearrange_array_elements_by_sign.rb)                                              |
+| 2150. Find All Lonely Numbers in the Array                                          | [Link](https://leetcode.com/problems/find-all-lonely-numbers-in-the-array/)                                          | [Link](./lib/medium/2150_find_all_lonely_numbers_in_the_array.rb)                                          | [Link](./test/medium/test_2150_find_all_lonely_numbers_in_the_array.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)                                                   |
 | 2429. Minimize XOR                                                                  | [Link](https://leetcode.com/problems/minimize-xor/)                                                                  | [Link](./lib/medium/2429_minimize_xor.rb)                                                                  | [Link](./test/medium/test_2429_minimize_xor.rb)                                                                  |
 | 2657. Find the Prefix Common Array of Two Arrays                                    | [Link](https://leetcode.com/problems/find-the-prefix-common-array-of-two-arrays/)                                    | [Link](./lib/medium/2657_find_the_prefix_common_array_of_two_arrays.rb)                                    | [Link](./test/medium/test_2657_find_the_prefix_common_array_of_two_arrays.rb)                                    |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 42ae4fac..4588a46e 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 = '9.0.5'
+  s.version = '9.0.6'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/2150_find_all_lonely_numbers_in_the_array.rb b/lib/medium/2150_find_all_lonely_numbers_in_the_array.rb
new file mode 100644
index 00000000..756797a6
--- /dev/null
+++ b/lib/medium/2150_find_all_lonely_numbers_in_the_array.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/find-all-lonely-numbers-in-the-array/
+# @param {Integer[]} nums
+# @return {Integer[]}
+def find_lonely(nums)
+  nums_with_count = ::Hash.new(0).tap { |h| nums.each { |num| h[num] += 1 } }
+  result = []
+
+  nums.each do |num|
+    result << num if nums_with_count[num] == 1 && !nums_with_count.key?(num - 1) && !nums_with_count.key?(num + 1)
+  end
+
+  result
+end
diff --git a/test/medium/test_2150_find_all_lonely_numbers_in_the_array.rb b/test/medium/test_2150_find_all_lonely_numbers_in_the_array.rb
new file mode 100644
index 00000000..183290bd
--- /dev/null
+++ b/test/medium/test_2150_find_all_lonely_numbers_in_the_array.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/2150_find_all_lonely_numbers_in_the_array'
+require 'minitest/autorun'
+
+class FindAllLonelyNumbersInTheArrayTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      [10, 8],
+      find_lonely(
+        [10, 6, 5, 8]
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      [1, 5],
+      find_lonely(
+        [1, 3, 5, 3]
+      )
+    )
+  end
+end