Advent of Code, day 10

day10.rb

#!/usr/bin/env ruby

# http://adventofcode.com/day/10

INPUT = "1113222113"

def look_and_say(s)
  s.gsub(/(.)\1*/) do
    "#{$&.size}#{$1}"
  end
end

def look_and_say_repeatedly(s, count)
  count.times do
    s = look_and_say(s)
  end
  s
end

[40, 50].each do |count|
  puts look_and_say_repeatedly(INPUT, count).length
end