Fibonacci

Fibonacci numberWikipedia

Memorized version

JavaScript

const fibonacci = (n, p = 0, c = 1, s = 0) => (s >= n ? p : fibonacci(n, c, p + c, s + 1));

Python

def fibonacci(n, p=0, c=1, s=0, cache={"largestStep": 0}):
    if cache.get(n):
        return cache[n]

    if cache["largestStep"] > s:
        _s = cache["largestStep"]
        _p = cache[_s]
        _c = cache[_s - 1] + _p
        return fibonacci(n, _c, _p + _c, _s + 1)

    cache["largestStep"] = s
    cache[s] = p
    return fibonacci(n, c, p + c, s + 1)