tidy numbers

problemB.rb

#!/usr/bin/env ruby

require 'set'

def is_tidy(n)
  narr = n.to_s.split('')
  snarr = narr.sort
  narr.join('') == snarr.join('')
end

def find_previous_tidy_number(n)
  (n.downto 1).each do |x|
    return x if is_tidy(x)
  end
end

def process(line)
  find_previous_tidy_number(Integer(line))
end

ARGF.each_with_index do |line, idx|
  next if idx.zero?

  puts "Case ##{idx}: #{process(line.strip)}"
end

# Usage: ./problemB.rb < input.txt > output.txt