dynamic programming fibonacci

dynamic_fib.rb

# Dynamic Programming for calculating nth Fibonacci Number
# Ian Taylor, 2017
def dp_fib(n, memo={})
	return memo[n] unless memo[n].nil?
	(n <= 2) ? f = 1 : f = dp_fib(n - 1, memo) + dp_fib(n - 2, memo)
	memo[n] = f
	f
end

# standard recursive Fibonacci
def fib(n)
	return 1 if n <= 2
	fib(n - 1) + fib(n - 2)
end