fibonacci.rb

require 'benchmark'

def fib_it(n)
  fib_nums = [0, 1]
  iterate = n-1
  iterate.times do
    num = fib_nums[-2] + fib_nums[-1]
    fib_nums << num
  end
  p fib_nums[-1]
end

# def fib(n)
#   if n < 2
#     n
#   else
#     fib(n-1) + fib(n-2)
#   end
# end

$cache = []

def fib(n)
  $cache[n] ||= if n < 2
    n
  else
    fib(n-1) + fib(n-2)
  end
end

puts Benchmark.measure {fib_it(3000)}
puts Benchmark.measure {fib(3000)}