triggered by [http://builder.japan.zdnet.com/sp/ruby-doukaku-panel/story/0,3800086254,20369264,00.htm]

hyphenize_numbers.rb

require 'enumerator'

def hyphenize_numbers *args
  src = args.map{|v| v.to_i}

  src.sort!.uniq!
  dst = [[ src[0] ]]
  src.each_cons(2) do |cons|
    if cons[1] - cons[0] > 1
      dst << []
    end
    dst.last << cons[1]
  end

  p src
  puts "--------"
  p dst

  dst.map! do |nums|
    if nums.length == 1
      nums[0].to_s
    else
      "#{nums.first}-#{nums.last}"
    end
  end

  puts "--------"
  puts dst.join(", ") + "."
end

if __FILE__ == $0
  SRC = [1, 2, 3, 5, 6, 7, 8, 9, 12, 14]
  hyphenize_numbers *SRC

=begin
  #=>
    [1, 2, 3, 5, 6, 7, 8, 9, 12, 14]
    --------
    [[1, 2, 3], [5, 6, 7, 8, 9], [12], [14]]
    --------
    1-3, 5-9, 12, 14.
=end
end