递归函数

# 递归求阶乘
def fun(n):
    if n <= 1:
        return n
    else:
        return n * fun(n - 1)


print([fun(i) for i in range(10)])

# 非递归求阶乘
def fun1(n):
    res = 1
    i = 1
    if n == 0:
        return 0
    while i <= n:
        res *= i
        i += 1
    return res


print([fun1(i) for i in range(10)])

# 递归求斐波拉切数列
def fun2(n):
    if n <= 1:
        return 1
    else:
        return fun2(n - 1) + fun2(n - 2)


print([fun2(i) for i in range(10)])

# 非递归求斐波拉切数列
def fun3(n):
    p = 0
    q = 1
    res = 0
    if n <= 1:
        return 1
    for i in range(n):
        res = p + q
        p = q
        q = res
    return res


print([fun3(i) for i in range(10)])

执行结果：

[0, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880]
[0, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880]
[1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
[1, 1, 2, 3, 5, 8, 13, 21, 34, 55]