[leetcode]202. Happy Number

class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        flag = set()
        while True:
            n = self.nextnum(n)
            if n == 1:
                return True
            if n not in flag:
                flag.add(n)
            else:
                return False
    def nextnum(self,num):
        res = 0
        while num:
            ge = num%10
            num /= 10
            res += ge**2
        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