guessing game (ruby)

gistfile1.rb

# solution to https://www.reddit.com/r/dailyprogrammer/comments/pii6j/difficult_challenge_1/

def main
  lower_bound = 1
  upper_bound = 100
  puts "Think of a number between 1 and 100, inclusive."
  puts "At each guess, answer with 'l' to indicate your number is lower than the guess, 'h' to indicate your number is higher than the guess, or 'y' to indicate the guess is correct."
  while true
    guess = (lower_bound + upper_bound) / 2
    puts "Is #{guess} your number?"
    input = gets
    case input.strip
    when "l"    # the number is less than than `guess`
      upper_bound = guess - 1
    when "h"    # the number is greater than `guess`
      lower_bound = guess + 1
    when "y"    # `guess` is the correct number, so bail out
      puts "Your number is #{guess}."
      break
    end
    raise "You lied! You didn't pick a number between 1 and 100!" unless lower_bound <= upper_bound
  end
end

main