diff --git a/README.md b/README.md
index da41b8b8..98fbeba0 100644
--- a/README.md
+++ b/README.md
@@ -650,3 +650,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 126. Word Ladder II                           | [Link](https://leetcode.com/problems/word-ladder-ii/)                            | [Link](./lib/hard/126_word_ladder_ii.rb)                           | [Link](./test/hard/test_126_word_ladder_ii.rb)                           |
 | 233. Number of Digit One                      | [Link](https://leetcode.com/problems/number-of-digit-one/)                       | [Link](./lib/hard/233_number_of_digit_one.rb)                      | [Link](./test/hard/test_233_number_of_digit_one.rb)                      |
 | 239. Sliding Window Maximum                   | [Link](https://leetcode.com/problems/sliding-window-maximum/)                    | [Link](./lib/hard/239_sliding_window_maximum.rb)                   | [Link](./test/hard/test_239_sliding_window_maximum.rb)                   |
+| 297. Serialize and Deserialize Binary Tree    | [Link](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/)     | [Link](./lib/hard/297_serialize_and_deserialize_binary_tree.rb)    | [Link](./test/hard/test_297_serialize_and_deserialize_binary_tree.rb)    |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 3915f243..4eef5154 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 = '7.8.0'
+  s.version = '7.8.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/hard/297_serialize_and_deserialize_binary_tree.rb b/lib/hard/297_serialize_and_deserialize_binary_tree.rb
new file mode 100644
index 00000000..e71e0548
--- /dev/null
+++ b/lib/hard/297_serialize_and_deserialize_binary_tree.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
+# @param {TreeNode} root
+# @return {String}
+def serialize_binary_tree(root)
+  preorder =
+    lambda do |node|
+      return [nil] unless node
+
+      [node.val] + preorder.call(node.left) + preorder.call(node.right)
+    end
+
+  preorder.call(root).to_json
+end
+
+# @param {String} data
+# @return {TreeNode}
+def deserialize_binary_tree(data)
+  return if data.empty?
+
+  helper =
+    lambda do |preorder|
+      return if preorder.empty?
+
+      current = preorder.shift
+
+      return unless current
+
+      root = ::TreeNode.new(current)
+      root.left = helper.call(preorder)
+      root.right = helper.call(preorder)
+
+      root
+    end
+
+  helper.call(::JSON.parse(data))
+end
diff --git a/test/hard/test_297_serialize_and_deserialize_binary_tree.rb b/test/hard/test_297_serialize_and_deserialize_binary_tree.rb
new file mode 100644
index 00000000..810e97a6
--- /dev/null
+++ b/test/hard/test_297_serialize_and_deserialize_binary_tree.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/common/binary_tree'
+require_relative '../../lib/hard/297_serialize_and_deserialize_binary_tree'
+require 'minitest/autorun'
+
+class SerializeAndDeserializeBinaryTreeTest < ::Minitest::Test
+  def test_default_one
+    assert(
+      ::TreeNode.are_equals(
+        ::TreeNode.new(
+          1,
+          ::TreeNode.new(2),
+          ::TreeNode.new(
+            3,
+            ::TreeNode.new(4),
+            ::TreeNode.new(5)
+          )
+        ),
+        deserialize_binary_tree(
+          serialize_binary_tree(
+            ::TreeNode.new(
+              1,
+              ::TreeNode.new(2),
+              ::TreeNode.new(
+                3,
+                ::TreeNode.new(4),
+                ::TreeNode.new(5)
+              )
+            )
+          )
+        )
+      )
+    )
+  end
+
+  def test_default_two
+    assert(
+      ::TreeNode.are_equals(
+        nil,
+        deserialize_binary_tree(
+          serialize_binary_tree(
+            nil
+          )
+        )
+      )
+    )
+  end
+end