Add Ruby solution for 2024 day 19

src/2024/19/solve.rb

···
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+PATTERNS = ARGF.readline.split(', ').map(&:strip)
+DESIGNS = ARGF.read.strip.lines.map(&:strip)
+
+# REGEX = %r{^(?:#{PATTERNS.join('|')})+$}
+
+$counts = {}
+
+def solve(design)
+  return $counts[design] if $counts.key?(design)
+  return 1 if design == ''
+  $counts[design] = PATTERNS.select { design.start_with?(_1) }.sum do |pattern|
+    solve(design[pattern.size..])
+  end
+end
+
+# puts DESIGNS.count { _1 =~ REGEX }
+puts DESIGNS.count { solve(_1) > 0 }
+puts DESIGNS.sum { solve _1 }