Anibel - Fibonacci - Edges

[anibelamerica]

Time complexity is O(n) where n is the value of the integer argument passed to the method.

Space complextiy is O(n) where n is also the value of the argument. Since we are using recursion, space in memory scales linearly for every recursive call to the method.

[shrutivanw]

Nice work thinking about this recursively. It turns out that the space complexity of the recursive approach to fibonacci, like in your algorithm results in a time complexity of O(2^n). You already know that exponential is one of the worst time complexity. Also, like you called out, the space complexity of this algorithm will be O(n) due to the call stack space it uses. We will be looking at this recursive approach to fibonacci later in class. Feel free to take a look at the later slides in https://drive.google.com/file/d/0B__DV26QHsH4bWJmS1A0QXBad1U/view?usp=sharing if you're curious. (P.S: play the slide show in Google slides so you can see the animations)

With that in mind, can you think of an algorithm to approach this iteratively instead of recursively? The iterative approach will have better time and space complexity than your current recursive algorithm, and is hence a more efficient solution. Once you have given it some thought, compare your iterative solution with https://github.com/Ada-C10/fibonacci/blob/solution/lib/fibonacci.rb

Slack me if you'd like to discuss further.