pop.rb

#takes a dollar ammount and return the number of purchased bottles plus the maximum number of bottles possible with recyling
def total_bottles_from_purchase(amt)
  amt = amt / 2 #get the number of purchased bottles
  #Track the bottles, and caps not redeemed. Track the number of purchased, and free bottles recieved
  tracker = {bottles:amt,caps:amt,purchased:amt,free:0}
  while (tracker[:bottles] >= 2) || (tracker[:caps] >= 4)
    #get the number of new free bottles from recycling
    free  = tracker[:bottles] / 2
    free += tracker[:caps] / 4
    #remove reedemed bottles and caps
    tracker[:bottles] %= 2
    tracker[:caps] %= 4
    #put the new bottles in to tracker
    tracker[:free] += free
    tracker[:bottles] += free
    tracker[:caps] += free
  end
  #Add the total number of bottles recieved
  tracker[:total] = tracker[:purchased] + tracker[:free]
  return tracker
end

while true do
  puts "Put a dolar amount (eg: 20) to find your savings, or exit to stop"
  user = gets().chomp.strip.downcase
  puts case user
    when "exit"
      puts "Exiting"
      return
    when /\d/
      save = total_bottles_from_purchase(user.to_i)
      puts "You would have #{save[:total]} bottles, only #{save[:purchased]} of which you paid for!\nThat means you got #{save[:free]} bottles for free!\nYou still have #{save[:caps]} Bottle caps, and #{save[:bottles]} bottles to recycle, if you buy some more bottles you can recycle these!"
    else
      puts "I couldn't understand your input, sorry."
    end
end