Solution for Euler #25 in Ruby w/ memoization

euler25.rb

# http://projecteuler.net/index.php?section=problems&id=25

# There are memoization libs, but i had it at my 
# fingertips anyway ..
def memoize(name)
  cache = {}
  (class << self; self; end).send(:define_method, name) do |*args|
    cache[args] = super(*args) unless cache.has_key?(args)
    cache[args]
  end
end

# Naive recursion
def fib(n)
  return n if n < 2
  fib(n-1) + fib(n-2)
end

# Enable memoization
memoize(:fib)

require "benchmark"

i = 1
limit = 10**999
puts Benchmark.measure { i += 1 while fib(i) < limit }.format("%r")
puts i

# => (0.030987)
# => 4782