Completed fibonacci challenge #13
Conversation
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Nice work attempting both iterative and recursive solutions. The space complexity of your iterative algorithm is O(n) because you're maintaining a results array. The results array will get as large as the input parameter, n before the final result is computed and returned. Can you think of how you may tweak the algorithm to not require the results' array and instead only maintain the previous two fibonacci numbers computed thus far in two separate integer values? Once you've given it some thought, compare your improved algorithm with mine on https://github.com/Ada-C10/fibonacci/blob/solution/lib/fibonacci.rb As you called out, the recursive approach, like the one you attempted takes much longer. It requires exponential time complexity to be precise i.e. O(2 ^ n). It also needs the call stack space which takes up O(n) space. 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) Slack me if you'd like to discuss further. |
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