Question

帮忙看看这个python代码错在哪了？

# coding=utf-8

m = {0:0,1:1}

def fib(n):
if not n in m:
m[n] = fib(n-1) + fib(n-2)
return m[n]

if __name__ == "__main__":
f = fib(10)
print(f)

Answer 1

没有发现错误，可以运行啊，你是不是需要检查一下缩进

追问

缩进是自动生成的，应该问题不大。下面是报的一堆错误。运行环境是pycharm2018版本的
Traceback (most recent call last):
File "D:/lq/Fibonacci_recursion.py", line 12, in
f = fib(10)
File "D:/lq/Fibonacci_recursion.py", line 8, in fib
m[n] = fib(n-1) + fib(n-2)
TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'
Process finished with exit code 1

追答

我在pycharm里又试了一下，确实是正常运行的

你可以打印一下数据类型，我这里都是int，你看一下你那里是不是出现了None

Answer 2

>>> m = {0:0,1:1}
>>> m
{0: 0, 1: 1}
>>> def fib(n):
if not n in m:
m[n] = fib(n-1) + fib(n-2)
return m[n]
SyntaxError: expected an indented block
>>> def fib(n):
if not n in m:
m[n] = fib(n-1) + fib(n-2)
return m[n]

>>> if __name__ == "__main__":
f = fib(10)
print(f)

Traceback (most recent call last):
File "<pyshell#6>", line 2, in <module>
f = fib(10)
File "<pyshell#4>", line 3, in fib
m[n] = fib(n-1) + fib(n-2)
File "<pyshell#4>", line 3, in fib
m[n] = fib(n-1) + fib(n-2)
File "<pyshell#4>", line 3, in fib
m[n] = fib(n-1) + fib(n-2)
[Previous line repeated 6 more times]
TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'

Answer 3

代码没问题，重新整理一下缩进就可以了