euler17.rb

   1 require 'logger'
   2 log = Logger.new(STDERR)
   3 log.level = Logger::WARN
   4
   5 $words = {1 => 'one',
   6           2 => 'two',
   7           3 => 'three',
   8           4 => 'four',
   9           5 => 'five',
  10           6 => 'six',
  11           7 => 'seven',
  12           8 => 'eight',
  13           9 => 'nine',
  14          10 => 'ten',
  15          11 => 'eleven',
  16          12 => 'twelve',
  17          13 => 'thirteen',
  18          14 => 'fourteen',
  19          15 => 'fifteen',
  20          16 => 'sixteen',
  21          17 => 'seventeen',
  22          18 => 'eighteen',
  23          19 => 'nineteen',
  24          20 => 'twenty',
  25          30 => 'thirty',
  26          40 => 'forty',
  27          50 => 'fifty',
  28          60 => 'sixty',
  29          70 => 'seventy',
  30          80 => 'eighty',
  31          90 => 'ninety',
  32         100 => 'hundred',
  33        1000 => 'thousand'}
  34
  35 def words_of_number(n)
  36   case n
  37   when (1..20)
  38     [$words[n]]
  39   when (21..99)
  40     [$words[n.div(10) * 10], $words[n % 10]]
  41   when (100..999)
  42     [$words[n.div(100)], 'hundred'] + (n % 100 == 0 ? [] : ['and'] + words_of_number(n % 100))
  43   when 1000
  44     ['one', 'thousand']
  45   end
  46 end
  47
  48 if __FILE__==$0
  49   words = []
  50   1.upto(1000) do |i|
  51     words += words_of_number(i)
  52     log.info { "Number #{i} gives words #{words_of_number i}" }
  53   end
  54
  55   puts words.join('').length
  56 end
  57
  58 log.close