Write an algorithm to determine if a number is "happy".
A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.
Example: 19 is a happy number
- 12 + 92 = 82
- 82 + 22 = 68
- 62 + 82 = 100
- 12 + 02 + 02 = 1
class Solution(object): def isHappy(self, n): """ :type n: int :rtype: bool """ key = set() s = str(n) key.add(s) re = 0 while True: for i in range(len(s)): re += int(s[i])**2 if re == 1: return True s = str(re) re = 0 if s in key: return False else: key.add(s)