Fibonacci with memoization

fib_memo.rb

memo = Hash.new(0)

def fib_rec (number, memo)
	if number == 0
		return number
	elsif (number == 1) || (number == 2)
		return 1
	end
  if (memo.has_key?(number))
    return memo[number]
  end
  puts "computing #{number}"
	result = fib_rec(number - 1, memo) + fib_rec(number - 2, memo)
  memo.store(number, result)
  return result
end


puts fib_rec(7, memo)
# computing 7
# computing 6
# computing 5
# computing 4
# computing 3
# => 13

# in the same time without memoization
# computing 7
# computing 6
# computing 5
# computing 4
# computing 3
# computing 3
# computing 4
# computing 3
# computing 5
# computing 4
# computing 3
# computing 3
# =>13