LeetCode 202. Happy Number

'''
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.
'''

class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        mem = {}
        while True:
            if n == 1:
                return True
            elif n in mem:
                return False
            else:
                mem[n]=1
                temp = 0
                for i in str(n):
                    temp += int(i)**2
                n = temp