类中的递归函数错误: python 2.7中没有定义全局名称'XXX‘，但在python 3中工作正常

Question

我在Class中写了一个递归函数，它在python 3中运行良好，但在python 2中不起作用。我想知道我应该如何在python 2中修复它

class Solution:
def jumpFloor(self, number):
    # write code here
    if number == 1 or number == 2:
        ways = number
        return ways
    elif number > 2:
        return jumpFloor(number-1) + jumpFloor(number-2)

test = Solution()
for i in range(8):
    print(test.jumpFloor(i))


#In python 3, the results are shown like:    
None
1
2
3
5
8
13
21

#But running the same code in python 2, it says:
global name 'jumpFloor' is not defined

Answer 1

尝试调用self.jumpFloor()而不是简单的jumpFloor() (并确保缩进正确)：

class Solution:

    def jumpFloor(self, number):

        if 1 <= number <= 2:
            return number

        if number > 2:
            return self.jumpFloor(number - 1) + self.jumpFloor(number - 2)

test = Solution()

for i in range(8):
    print(test.jumpFloor(i))

这在Python2和Python3中都适用。递归例程似乎不完整，因为它不能处理0(至少)，更不用说过滤掉负数了。