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class Memoized
  attr_reader :factorial_memo
  def initialize
    @factorial_memo = {}
  end

  def factorial(n)
    puts n
    @factorial_memo[n] ||= if n < 1
      1
    else
      n * factorial(n-1)
    end
  end
end

memoized = Memoized.new

5.downto(1) { |i| puts "\t#{memoized.factorial(i)}" }

puts memoized.factorial_memo.inspect