2024-07-10 v. 6.1.1: added "38. Count and Say"

Author: fartem

README.md

@@ -476,3 +476,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 33. Search in Rotated Sorted Array                          | [Link](https://leetcode.com/problems/search-in-rotated-sorted-array/)                          | [Link](./lib/medium/33_search_in_rotated_sorted_array.rb)                          |
 | 34. Find First and Last Position of Element in Sorted Array | [Link](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/) | [Link](./lib/medium/34_find_first_and_last_position_of_element_in_sorted_array.rb) |
 | 36. Valid Sudoku                                            | [Link](https://leetcode.com/problems/valid-sudoku/)                                            | [Link](./lib/medium/36_valid_sudoku.rb)                                            |
+| 38. Count and Say                                           | [Link](https://leetcode.com/problems/count-and-say/)                                           | [Link](./lib/medium/38_count_and_say.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 = '6.1.0'
+  s.version = '6.1.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[bin/leetcode-ruby README.md LICENSE]
   s.executable = 'leetcode-ruby'

lib/medium/38_count_and_say.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/count-and-say/
+# @param {Integer} n
+# @return {String}
+def count_and_say(n)
+  return '1' if n == 1
+
+  str = count_and_say(n - 1)
+  result = []
+  count = 1
+  i = 1
+  while i < str.length
+    if str[i] == str[i - 1]
+      count += 1
+    else
+      result << (count + 48).chr
+      result << str[i - 1]
+
+      count = 1
+    end
+
+    i += 1
+  end
+
+  result << (count + 48).chr
+  result << str[i - 1]
+
+  result.join
+end

test/medium/test_38_count_and_say.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/38_count_and_say'
+require 'minitest/autorun'
+
+class CountAndSayTest < ::Minitest::Test
+  def test_default
+    assert_equal('1211', count_and_say(4))
+    assert_equal('1', count_and_say(1))
+  end
+end