Python 斐波那契数列优化

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

print(fib(30))
1346269

def cache(fun):
fibs = {}

def wrapper(n):
if n in fibs:
return fibs

res = fun(n)
fibs
= res
return res

return wrapper

@cache
def fib(n):
return 1 if n < 2 else fib(n - 1) + fib(n - 2)

print(fib(30))
1346269

import numpy as np

def power(m, n):
if n <= 1:
return m

t = power(m, n // 2)
if n % 2 == 0:
return np.dot(t, t)

return np.dot(m, np.dot(t, t))

def fib(n):
mat = np.array([[1, 1], [1, 0]])
t = power(mat, n)[0][1]
print(t)

for i in range(1, 40):
fib(i)

1
1
2
3
5
8
13
21
34
55
89