• + 0 comments

    Here is my Python solution!

    def alternate(s):
        lens = [0]
        letters = list(set(list(s)))
        for letter1 in range(len(letters)):
            for letter2 in range(letter1 + 1, len(letters)):
                two = []
                for letter in s:
                    if letter == letters[letter1]:
                        if two:
                            if two[-1] == letters[letter2]:
                                two.append(letter)
                            else:
                                two = []
                                break
                        else:
                            two.append(letter)
                    elif letter == letters[letter2]:
                        if two:
                            if two[-1] == letters[letter1]:
                                two.append(letter)
                            else:
                                two = []
                                break
                        else:
                            two.append(letter)
                lens.append(len(two))
        return max(lens)