diff --git a/README.md b/README.md
index 1cfb8de3..aaddef21 100644
--- a/README.md
+++ b/README.md
@@ -683,6 +683,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 1339. Maximum Product of Splitted Binary Tree                                       | [Link](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree/)                                       | [Link](./lib/medium/1339_maximum_product_of_splitted_binary_tree.rb)                                       | [Link](./test/medium/test_1339_maximum_product_of_splitted_binary_tree.rb)                                       |
 | 1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold | [Link](https://leetcode.com/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/) | [Link](./lib/medium/1343_number_of_sub_arrays_of_size_k_and_average_greater_than_or_equal_to_threshold.rb) | [Link](./test/medium/test_1343_number_of_sub_arrays_of_size_k_and_average_greater_than_or_equal_to_threshold.rb) |
 | 1347. Minimum Number of Steps to Make Two Strings Anagram                           | [Link](https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram/)                           | [Link](./lib/medium/1347_minimum_number_of_steps_to_make_two_strings_anagram.rb)                           | [Link](./test/medium/test_1347_minimum_number_of_steps_to_make_two_strings_anagram.rb)                           |
+| 1358. Number of Substrings Containing All Three Characters                          | [Link](https://leetcode.com/problems/number-of-substrings-containing-all-three-characters/)                          | [Link](./lib/medium/1358_number_of_substrings_containing_all_three_characters.rb)                          | [Link](./test/medium/test_1358_number_of_substrings_containing_all_three_characters.rb)                          |
 | 1400. Construct K Palindrome Strings                                                | [Link](https://leetcode.com/problems/construct-k-palindrome-strings/)                                                | [Link](./lib/medium/1400_construct_k_palindrome_strings.rb)                                                | [Link](./test/medium/test_1400_construct_k_palindrome_strings.rb)                                                |
 | 2116. Check if a Parentheses String Can Be Valid                                    | [Link](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/)                                    | [Link](./lib/medium/2116_check_if_a_parentheses_string_can_be_valid.rb)                                    | [Link](./test/medium/test_2116_check_if_a_parentheses_string_can_be_valid.rb)                                    |
 | 2425. Bitwise XOR of All Pairings                                                   | [Link](https://leetcode.com/problems/bitwise-xor-of-all-pairings/)                                                   | [Link](./lib/medium/2425_bitwise_xor_of_all_pairings.rb)                                                   | [Link](./test/medium/test_2425_bitwise_xor_of_all_pairings.rb)                                                   |
diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 869726a9..6f5e9f0c 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 = '8.5.0'
+  s.version = '8.5.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/1358_number_of_substrings_containing_all_three_characters.rb b/lib/medium/1358_number_of_substrings_containing_all_three_characters.rb
new file mode 100644
index 00000000..680b4c70
--- /dev/null
+++ b/lib/medium/1358_number_of_substrings_containing_all_three_characters.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/number-of-substrings-containing-all-three-characters/
+# @param {String} s
+# @return {Integer}
+def number_of_substrings(s)
+  chars = ::Array.new(3, 0)
+  left = 0
+  result = 0
+
+  (0...s.size).each do |i|
+    chars[s[i].ord - 97] += 1
+
+    while chars[0].positive? && chars[1].positive? && chars[2].positive?
+      result += s.size - i
+
+      chars[s[left].ord - 97] -= 1
+
+      left += 1
+    end
+  end
+
+  result
+end
diff --git a/test/medium/test_1358_number_of_substrings_containing_all_three_characters.rb b/test/medium/test_1358_number_of_substrings_containing_all_three_characters.rb
new file mode 100644
index 00000000..e42cfc32
--- /dev/null
+++ b/test/medium/test_1358_number_of_substrings_containing_all_three_characters.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/1358_number_of_substrings_containing_all_three_characters'
+require 'minitest/autorun'
+
+class NumberOfSubstringsContainingAllThreeCharactersTest < ::Minitest::Test
+  def test_default_one = assert_equal(10, number_of_substrings('abcabc'))
+
+  def test_default_two = assert_equal(3, number_of_substrings('aaacb'))
+
+  def test_default_three = assert_equal(1, number_of_substrings('abc'))
+end