diff --git a/README.md b/README.md
index 970602b1..d0dda127 100644
--- a/README.md
+++ b/README.md
@@ -605,3 +605,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 652. Find Duplicate Subtrees                                    | [Link](https://leetcode.com/problems/find-duplicate-subtrees/)                                    | [Link](./lib/medium/652_find_duplicate_subtrees.rb)                                    | [Link](./test/medium/test_652_find_duplicate_subtrees.rb)                                    |
 | 654. Maximum Binary Tree                                        | [Link](https://leetcode.com/problems/maximum-binary-tree/)                                        | [Link](./lib/medium/654_maximum_binary_tree.rb)                                        | [Link](./test/medium/test_654_maximum_binary_tree.rb)                                        |
 | 659. Split Array into Consecutive Subsequences                  | [Link](https://leetcode.com/problems/split-array-into-consecutive-subsequences/)                  | [Link](./lib/medium/659_split_array_into_consecutive_subsequences.rb)                  | [Link](./test/medium/test_659_split_array_into_consecutive_subsequences.rb)                  |
+| 662. Maximum Width of Binary Tree                               | [Link](https://leetcode.com/problems/maximum-width-of-binary-tree/)                               | [Link](./lib/medium/662_maximum_width_of_binary_tree.rb)                               | [Link](./test/medium/test_662_maximum_width_of_binary_tree.rb)                               |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 94c688e8..79eac456 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 = '7.4.0'
+  s.version = '7.4.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/662_maximum_width_of_binary_tree.rb b/lib/medium/662_maximum_width_of_binary_tree.rb
new file mode 100644
index 00000000..ef0b3c75
--- /dev/null
+++ b/lib/medium/662_maximum_width_of_binary_tree.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/maximum-width-of-binary-tree/
+# @param {TreeNode} root
+# @return {Integer}
+def width_of_binary_tree(root)
+  result = 1
+  nodes = [::TreeNodePair.new(root, 0)]
+  until nodes.empty?
+    size = nodes.size
+    min = +1.0 / 0.0
+    max = 0
+    (0...size).each do |_i|
+      pair = nodes.delete_at(0)
+      min = [min, pair.value].min
+      max = [max, pair.value].max
+
+      left = pair.node.left
+      right = pair.node.right
+
+      nodes << ::TreeNodePair.new(left, pair.value * 2 + 1) if left
+      nodes << ::TreeNodePair.new(right, pair.value * 2 + 2) if right
+    end
+
+    result = [result, max - min + 1].max
+  end
+
+  result
+end
+
+private
+
+# TreeNodePair
+class TreeNodePair
+  attr_accessor :node, :value
+
+  # @param {TreeNode} node
+  # @param {Integer} value
+  def initialize(node, value)
+    @node = node
+    @value = value
+  end
+end
diff --git a/test/medium/test_662_maximum_width_of_binary_tree.rb b/test/medium/test_662_maximum_width_of_binary_tree.rb
new file mode 100644
index 00000000..0b85f0b8
--- /dev/null
+++ b/test/medium/test_662_maximum_width_of_binary_tree.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/medium/662_maximum_width_of_binary_tree'
+require 'minitest/autorun'
+
+class MaximumWidthOfBinaryTreeTest < ::Minitest::Test
+  def test_default_one
+    assert_equal(
+      4,
+      width_of_binary_tree(
+        ::TreeNode.new(
+          1,
+          ::TreeNode.new(
+            3,
+            ::TreeNode.new(5),
+            ::TreeNode.new(3)
+          ),
+          ::TreeNode.new(
+            2,
+            nil,
+            ::TreeNode.new(9)
+          )
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert_equal(
+      7,
+      width_of_binary_tree(
+        ::TreeNode.new(
+          1,
+          ::TreeNode.new(
+            3,
+            ::TreeNode.new(
+              5,
+              ::TreeNode.new(6),
+              nil
+            ),
+            nil
+          ),
+          ::TreeNode.new(
+            2,
+            nil,
+            ::TreeNode.new(
+              9,
+              ::TreeNode.new(7),
+              nil
+            )
+          )
+        )
+      )
+    )
+  end
+
+  def test_default_three
+    assert_equal(
+      2,
+      width_of_binary_tree(
+        ::TreeNode.new(
+          1,
+          ::TreeNode.new(
+            3,
+            ::TreeNode.new(5),
+            nil
+          ),
+          ::TreeNode.new(2)
+        )
+      )
+    )
+  end
+end