题目：

题解：

def isHappy(self, n: int) -> bool:

    cycle_members = {4, 16, 37, 58, 89, 145, 42, 20}

    def get_next(number):
        total_sum = 0
        while number > 0:
            number, digit = divmod(number, 10)
            total_sum += digit ** 2
        return total_sum

    while n != 1 and n not in cycle_members:
        n = get_next(n)

    return n == 1