Fibonacci

gistfile1.rb

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

def fib_with_caching(n)
  @fib_cache    ||= {}
  @fib_cache[n] ||= fib_without_caching(n)
end

alias_method_chain :fib, :caching