diff --git a/README.md b/README.md
index 6988954..ec7d66b 100644
--- a/README.md
+++ b/README.md
@@ -526,3 +526,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 151. Reverse Words in a String                                  | [Link](https://leetcode.com/problems/reverse-words-in-a-string/)                                  | [Link](./lib/medium/151_reverse_words_in_a_string.rb)                                  | [Link](./test/medium/test_151_reverse_words_in_a_string.rb)                                  |
 | 155. Min Stack                                                  | [Link](https://leetcode.com/problems/min-stack/)                                                  | [Link](./lib/medium/155_min_stack.rb)                                                  | [Link](./test/medium/test_155_min_stack.rb)                                                  |
 | 165. Compare Version Numbers                                    | [Link](https://leetcode.com/problems/compare-version-numbers/)                                    | [Link](./lib/medium/165_compare_version_numbers.rb)                                    | [Link](./test/medium/test_165_compare_version_numbers.rb)                                    |
+| 167. Two Sum II - Input Array Is Sorted                         | [Link](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/)                           | [Link](./lib/medium/167_two_sum_ii_input_array_is_sorted.rb)                           | [Link](./test/medium/test_167_two_sum_ii_input_array_is_sorted.rb)                           |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 570de6c..0e78c0e 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 = '6.6.0'
+  s.version = '6.6.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/167_two_sum_ii_input_array_is_sorted.rb b/lib/medium/167_two_sum_ii_input_array_is_sorted.rb
new file mode 100644
index 0000000..e0bb0d8
--- /dev/null
+++ b/lib/medium/167_two_sum_ii_input_array_is_sorted.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/
+# @param {Integer[]} numbers
+# @param {Integer} target
+# @return {Integer[]}
+def two_sum167(numbers, target)
+  start = 0
+  nd = numbers.size - 1
+  until start == nd
+    sum = numbers[start] + numbers[nd]
+
+    if sum > target
+      nd -= 1
+    elsif sum < target
+      start += 1
+    else
+      break
+    end
+  end
+
+  [start + 1, nd + 1]
+end
diff --git a/test/medium/test_167_two_sum_ii_input_array_is_sorted.rb b/test/medium/test_167_two_sum_ii_input_array_is_sorted.rb
new file mode 100644
index 0000000..f83ad22
--- /dev/null
+++ b/test/medium/test_167_two_sum_ii_input_array_is_sorted.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/167_two_sum_ii_input_array_is_sorted'
+require 'minitest/autorun'
+
+class TwoSumIIInputArrayIsSortedTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      [1, 2],
+      two_sum167(
+        [2, 7, 11, 15],
+        9
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      [1, 3],
+      two_sum167(
+        [2, 3, 4],
+        6
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      [1, 2],
+      two_sum167(
+        [-1, 0],
+        -1
+      )
+    )
+  end
+
+  def test_additional_one
+    assert_equal(
+      [2, 3],
+      two_sum167(
+        [5, 25, 75],
+        100
+      )
+    )
+  end
+end