2024-07-04 v. 6.0.3: added "17. Letter Combinations of a Phone Number"

Author: fartem

README.md

@@ -468,3 +468,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 12. Integer to Roman                              | [Link](https://leetcode.com/problems/integer-to-roman/)                               | [Link](./lib/medium/12_integer_to_roman.rb)                              |
 | 15. 3Sum                                          | [Link](https://leetcode.com/problems/3sum/)                                           | [Link](./lib/medium/15_3sum.rb)                                          |
 | 16. 3Sum Closest                                  | [Link](https://leetcode.com/problems/3sum-closest/)                                   | [Link](./lib/medium/16_3sum_closest.rb)                                  |
+| 17. Letter Combinations of a Phone Number         | [Link](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)          | [Link](./lib/medium/17_letter_combinations_of_a_phone_number.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 = '6.0.2'
+  s.version = '6.0.3'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/medium/17_letter_combinations_of_a_phone_number.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/letter-combinations-of-a-phone-number/
+# @param {String} digits
+# @return {String[]}
+def letter_combinations(digits)
+  return [] if digits.empty?
+
+  buttons = %w[abc def ghi jkl mno prsq tuv wxyz]
+  result = ['']
+  digits.each_char do |c|
+    curr = buttons[c.ord - '2'.ord]
+    new_result = []
+    result.each do |layout|
+      (0...curr.length).each do |j|
+        new_result << layout + curr[j]
+      end
+    end
+
+    result = new_result
+  end
+
+  result
+end

test/medium/test_17_letter_combinations_of_a_phone_number.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/17_letter_combinations_of_a_phone_number'
+require 'minitest/autorun'
+
+class LetterCombinationsOfAPhoneNumberTest < ::Minitest::Test
+  def test_default
+    assert_equal(%w[ad ae af bd be bf cd ce cf], letter_combinations('23'))
+    assert_equal([], letter_combinations(''))
+    assert_equal(%w[a b c], letter_combinations('2'))
+  end
+end