diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index ecf47164..02685f43 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 = '8.2.5.3'
+  s.version = '8.2.5.4'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/test/hard/test_297_serialize_and_deserialize_binary_tree.rb b/test/hard/test_297_serialize_and_deserialize_binary_tree.rb
index 810e97a6..ea1b6bdc 100644
--- a/test/hard/test_297_serialize_and_deserialize_binary_tree.rb
+++ b/test/hard/test_297_serialize_and_deserialize_binary_tree.rb
@@ -9,25 +9,13 @@ 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)
-          )
+        ::TreeNode.build_tree(
+          [1, 2, 3, nil, nil, 4, 5]
         ),
         deserialize_binary_tree(
           serialize_binary_tree(
-            ::TreeNode.new(
-              1,
-              ::TreeNode.new(2),
-              ::TreeNode.new(
-                3,
-                ::TreeNode.new(4),
-                ::TreeNode.new(5)
-              )
+            ::TreeNode.build_tree(
+              [1, 2, 3, nil, nil, 4, 5]
             )
           )
         )
diff --git a/test/hard/test_968_binary_tree_cameras.rb b/test/hard/test_968_binary_tree_cameras.rb
index 8415c380..8c75b695 100644
--- a/test/hard/test_968_binary_tree_cameras.rb
+++ b/test/hard/test_968_binary_tree_cameras.rb
@@ -10,14 +10,8 @@ def test_default_one
     assert_equal(
       1,
       min_camera_cover(
-        ::TreeNode.new(
-          0,
-          ::TreeNode.new(
-            0,
-            ::TreeNode.new(0),
-            ::TreeNode.new(0)
-          ),
-          nil
+        ::TreeNode.build_tree(
+          [0, 0, nil, 0, 0]
         )
       )
     )
@@ -27,22 +21,8 @@ def test_default_two
     assert_equal(
       2,
       min_camera_cover(
-        ::TreeNode.new(
-          0,
-          ::TreeNode.new(
-            0,
-            ::TreeNode.new(
-              0,
-              ::TreeNode.new(
-                0,
-                nil,
-                ::TreeNode.new(0)
-              ),
-              nil
-            ),
-            nil
-          ),
-          nil
+        ::TreeNode.build_tree(
+          [0, 0, nil, 0, nil, 0, nil, nil, 0]
         )
       )
     )