這裡提供一個Two pointer的解法，有興趣的讀者可以看一下!
感謝作者，讓我們認識leetcode的好XD

class Solution:
    def calculateDigitSquaredSum(self, n : int) -> int:
        s = 0
        for c in str(n):
            s += int(c) ** 2
        return s
    
    def isHappy(self, n: int) -> bool: 
        slow = fast = n
        while True:
            slow = self.calculateDigitSquaredSum(slow)
            fast = self.calculateDigitSquaredSum(fast)
            fast = self.calculateDigitSquaredSum(fast)
            if slow == fast:
                break
        return fast == 1