题目描述:

题解：

用哈希集合检测循环

         def isHappy(self, n: int) -> bool:
        def get_next(n):
            total_sum = 0
            while n > 0:
                n, digit = divmod(n, 10)
                total_sum += digit ** 2
            return total_sum
        seen = set()
        while n != 1 and n not in seen:
            seen.add(n)
            n = get_next(n)
        return n == 1