diff --git a/README.md b/README.md
index 1984f94d..93daa07e 100644
--- a/README.md
+++ b/README.md
@@ -627,6 +627,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 823. Binary Trees With Factors                                  | [Link](https://leetcode.com/problems/binary-trees-with-factors/)                                  | [Link](./lib/medium/823_binary_trees_with_factors.rb)                                  | [Link](./test/medium/test_823_binary_trees_with_factors.rb)                                  |
 | 841. Keys and Rooms                                             | [Link](https://leetcode.com/problems/keys-and-rooms/)                                             | [Link](./lib/medium/841_keys_and_rooms.rb)                                             | [Link](./test/medium/test_841_keys_and_rooms.rb)                                             |
 | 852. Peak Index in a Mountain Array                             | [Link](https://leetcode.com/problems/peak-index-in-a-mountain-array/)                             | [Link](./lib/medium/852_peak_index_in_a_mountain_array.rb)                             | [Link](./test/medium/test_852_peak_index_in_a_mountain_array.rb)                             |
+| 856. Score of Parentheses                                       | [Link](https://leetcode.com/problems/score-of-parentheses/)                                       | [Link](./lib/medium/856_score_of_parentheses.rb)                                       | [Link](./test/medium/test_856_score_of_parentheses.rb)                                       |
 
 ### Hard
 
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 44e245c6..965adba9 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 = '7.6.6'
+  s.version = '7.6.7'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/856_score_of_parentheses.rb b/lib/medium/856_score_of_parentheses.rb
new file mode 100644
index 00000000..969b49a7
--- /dev/null
+++ b/lib/medium/856_score_of_parentheses.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/score-of-parentheses/
+# @param {String} s
+# @return {Integer}
+def score_of_parentheses(s)
+  stack = [0]
+  s.each_char do |c|
+    if c == '('
+      stack << 0
+    else
+      a = stack.delete_at(stack.size - 1)
+      b = stack.delete_at(stack.size - 1)
+
+      stack << b + [2 * a, 1].max
+    end
+  end
+
+  stack.last
+end
diff --git a/test/medium/test_856_score_of_parentheses.rb b/test/medium/test_856_score_of_parentheses.rb
new file mode 100644
index 00000000..dec6265b
--- /dev/null
+++ b/test/medium/test_856_score_of_parentheses.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/856_score_of_parentheses'
+require 'minitest/autorun'
+
+class ScoreOfParenthesesTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      1,
+      score_of_parentheses(
+        '()'
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      2,
+      score_of_parentheses(
+        '(())'
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      2,
+      score_of_parentheses(
+        '()()'
+      )
+    )
+  end
+end