2025-01-01 v. 7.6.1: added "10. Regular Expression Matching"

Author: fartem

README.md

@@ -627,6 +627,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 
 ### Hard
 
-| Name                           | Link to LeetCode                                                   | Link to solution                                    | Link to tests                                             |
-| ------------------------------ | ------------------------------------------------------------------ | --------------------------------------------------- | --------------------------------------------------------- |
-| 4. Median of Two Sorted Arrays | [Link](https://leetcode.com/problems/median-of-two-sorted-arrays/) | [Link](./lib/hard/4_median_of_two_sorted_arrays.rb) | [Link](./test/hard/test_4_median_of_two_sorted_arrays.rb) |
+| Name                            | Link to LeetCode                                                   | Link to solution                                     | Link to tests                                              |
+| ------------------------------- | ------------------------------------------------------------------ | ---------------------------------------------------- | ---------------------------------------------------------- |
+| 4. Median of Two Sorted Arrays  | [Link](https://leetcode.com/problems/median-of-two-sorted-arrays/) | [Link](./lib/hard/4_median_of_two_sorted_arrays.rb)  | [Link](./test/hard/test_4_median_of_two_sorted_arrays.rb)  |
+| 10. Regular Expression Matching | [Link](https://leetcode.com/problems/regular-expression-matching/) | [Link](./lib/hard/10_regular_expression_matching.rb) | [Link](./test/hard/test_10_regular_expression_matching.rb) |

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 = '7.6.0.1'
+  s.version = '7.6.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/hard/10_regular_expression_matching.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+@mem = {}
+
+# https://leetcode.com/problems/regular-expression-matching/
+# @param {String} s
+# @param {String} p
+# @return {Boolean}
+def is_match(s, p)
+  s = s.bytes
+  p = p.bytes
+  dp = ::Array.new(s.length + 1) { ::Array.new(p.length + 1, false) }
+  m = s.length
+  n = p.length
+  dp[m][n] = true
+
+  (0..m).reverse_each do |i|
+    (n - 1).downto(0) do |j|
+      first = i < m && (s[i] == p[j] || p[j] == 46)
+      dp[i][j] =
+        if p[j + 1] == 42
+          dp[i][j + 2] || (first && dp[i + 1][j])
+        else
+          first && dp[i + 1][j + 1]
+        end
+    end
+  end
+
+  dp[0][0]
+end

test/hard/test_10_regular_expression_matching.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/hard/10_regular_expression_matching'
+require 'minitest/autorun'
+
+class RegularExpressionMatchingTest < ::Minitest::Test
+  def test_default_one = assert(!is_match('aa', 'a'))
+
+  def test_default_two = assert(is_match('aa', 'a*'))
+
+  def test_default_three = assert(is_match('ab', '.*'))
+end