斐波那契数列的Python实现

  斐波那契数列的Python实现：递归实现、非递归实现、斐波那契数列生成器；

\[\begin{equation}
F(n)=
\begin{cases}
n & n=0, 1\\
F(n-1) + F(n-2) & n > 1
\end{cases}
\end{equation}
\]

---

递归实现:

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

非递归实现:

# python
def fib(n):
    if n <= 1:
        return n
    else:
        f1, f2, c = 0, 1, 0
        for i range(n-1):
            c = f1 + f2
            f1, f2 = f2, c
        return c

斐波那契数列生成器:

# python
def fib(n):
    a, b, iter = 1, 0, -1
    while iter < n:
        yield b
       # print(b)
        a, b = b, a+b
        iter += 1

for f in fib(10):
    print(f)