[leetcode]202. Happy Number

 1 class Solution(object):
 2     def isHappy(self, n):
 3         """
 4         :type n: int
 5         :rtype: bool
 6         """
 7         flag = set()
 8         while True:
 9             n = self.nextnum(n)
10             if n == 1:
11                 return True
12             if n not in flag:
13                 flag.add(n)
14             else:
15                 return False
16     def nextnum(self,num):
17         res = 0
18         while num:
19             ge = num%10
20             num /= 10
21             res += ge**2
22         return res

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.

求一个数是不是快乐的