[2017-05-29] Challenge #317 [Easy] Collatz Tag System

Collatz_Tag_System.rb

#[2017-05-29] Challenge #317 [Easy] Collatz Tag System
#https://www.reddit.com/r/dailyprogrammer/comments/6e08v6/20170529_challenge_317_easy_collatz_tag_system/

tag_keys = %w(a b c)
tag_system = %w(bc a aaa)
puts "what do i start with? (at least 3 chars, combination of a/b/c)"
tag = gets.chomp

while tag.length > 2
  case tag.chr
    when tag_keys[0]
      tag = tag[2..-1] + tag_system[0]
    when tag_keys[1]
      tag = tag[2..-1] + tag_system[1]
    when tag_keys[2]
      tag = tag[2..-1] + tag_system[2]
    end
  puts tag
end

puts tag[1]
puts "Done"

Could use splice! and perhaps a Hash system instead of 2 arrays