Fibonacci functions

fib_queue.py

#!/usr/bin/env python3

from collections import deque as queue

def fib_q(n):
    if n < 2:
        return n
    memo = queue((0, 1,), maxlen=2)
    for i in range(1, n):
        im2 = memo.popleft()
        im1 = memo[0]
        memo.append(im2 + im1)
    return memo.pop()

fib_recursive.py

#!/usr/bin/env python3

def fib_r(n):
    if n < 2:
        return n
    return fib_r(n-2) + fib_r(n-1)

fib_recursive_memoization.py

#!/usr/bin/env python3

from functools import lru_cache

@lru_cache(maxsize=10_000)
def fib_r(n):
    if n < 2:
        return n
    # do not exceed the recursion limit
    for i in range(512, n, 512):
        fib_r(i-1)
        fib_r(i)
    return fib_r(n-2) + fib_r(n-1)