题解 | #字符串排序#

input_str=input()
def custom_sort(input_strining):
    letters = []
    non_letters = []

    for char in input_strining:
        if char.isalpha():
            letters.append(char)
        else:
            non_letters.append(char)

    unique_letters = sorted(list(set([x.lower() for x in letters])))
    unique_letters
    letter_group = []
    for i in unique_letters:
        group = []
        for j in letters:
            if j.lower() == i:
                group.append(j)
        letter_group.append(group)
    for i in range(1, len(letter_group)):
        letter_group[0] += letter_group[i]
    letter_group[0]
    result = []
    non_letter_index = 0
    letter_index = 0

    for char in input_strining:
        if char.isalpha():
            result.append(letter_group[0][letter_index])
            letter_index += 1
        else:
            result.append(non_letters[non_letter_index])
            non_letter_index += 1

    return "".join(result)


print(custom_sort(input_str))