递归返回 python 中包含 2 个元素的列表

Question

i want the function to store a list or a tuple with two strings in it. The diffrent strings is dependent on wether the character is lower or upper case, if not in the alphabet it should be removed. The functions should be strictly recursive and no extra parameters to the function. how do i get this done?

def recursive(message):
        if message > 0:

               if message[0].islower():

                    return message[0] + recursive(message[1:]), 


               if message[0].isupper():
                    return message[0] + recursive(message[1:]),

               else:
                    return recursive(message[1:])



first, second = recursive("HalleLUJAh")

first should then hold ("alleh")
second should then hold ("HLUJA")

Answer 1

def split_case(sentence)
    lower, upper  = "", ""
        for char in sentence:
            if char.islower():
                lower += char
            else:
                upper += char
    return lower, upper

Answer 2

def recursive_split(message):
    if message:
        first, second = recursive_split(message[1:])
        if message[0].isupper():
            return first, message[0] + second
        else:
            return message[0] + first, second

    else:
        return "", ""

print(recursive_split("HalleLUJAh")) # ('alleh', 'HLUJA')

Answer 3

You can just use something like,

$ cat rec.py
def recursive(word):
    lower, upper = "", ""
    if word:
        if word[0].islower():
            lower += word[0]
            f, s = recursive(word[1:])
            lower += f
            upper += s
        else:
            upper += word[0]
            f, s = recursive(word[1:])
            lower += f
            upper += s
    return lower, upper

first, second = recursive("HalleLUJAh")
print(first, second)

Output:

$ python rec.py
('alleh', 'HLUJA')