您能告诉我代码有什么问题吗？

Question

When I call my fib function it doesn't return anything. Can you tell me what is it that I'm doing wrong?

def fib(n, List = []):
    if n > 0:
        if len(List) == 0 or len(List) == 1:
            List.append(1)
        else:
            List.append(List[len(List) - 2] + List[len(List) - 1])
        fib(n - 1, List)
    else:
        return List

l = fib(5)
print(l)  # >> None

Answer 1

Change fib(n - 1, List) to return fib(n - 1, List) :

def fib(n, List = []):
    if n > 0:
        if len(List) == 0 or len(List) == 1:
            List.append(1)
        else:
            List.append(List[len(List) - 2] + List[len(List) - 1])
        return fib(n - 1, List)
    else:
        return List