feat(maths): recursive calculating of Fibonacci numbers

[zFlxw]

This is an improvement to the algorithm for calculating the nth Fibonacci number, as the algorithm can be implemented recursively. Also, I have improved and structured the tests a bit different.

Feel free to share your thoughts and give feedback.

[appgurueu]

This is an improvement to the algorithm for calculating the nth Fibonacci number, as the algorithm can be implemented recursively.

No, the recursive implementation is not at all an improvement. It is much, much worse runtime-wise - the "dynamic programming" algorithm that was previously implemented runs in linear time, whereas this runs in exponential time.

You may still add the recursive version (if you also add a big warning), but you may not replace the preferable dynamic programming version.

The improvements to the tests are fine.

[zFlxw]

Alright, thank you for your feedback. So may I convert my changes to an additional closure and keep the original one also?

[appgurueu]

Yes, this is fine, but please don't duplicate the tests: Just parameterize the tests in terms of the function to be tested, then run once for the iterative, once for the recursive variant.

[zFlxw]

I am pretty new to writing tests in JS/TS, but hopefully I understood correctly what you meant. If not, please give feedback about the tests again. :)

[appgurueu]

What I had in mind when I said "parameterize the tests in terms of the function" was rather the following:

const test = func => it.each([[0, 0], [1, 1], [2, 1], [5, 5], [10, 55], [15, 610]])('fib(%i) = %i', (n, expected) => expect(func(n)).toBe(expected));
describe("Fibonacci iterative", () => test(nthFibonacci));
describe("Fibonacci recursive", () => test(nthFibonacciRecursively));

[zFlxw]

Thanks for clarifying, I have adjusted the tests.