leetcode happy number

https://leetcode.com/problems/happy-number/

记住如何从integer里面提取 digit，

while n:d = n % 10res.append(d)n /= 10

set 是用set()初始化而用add 更新的只要平方和的结果有重复，而且重复的不是1，那么就是false。参考http://bookshadow.com/weblog/2015/04/22/leetcode-happy-number/

class Solution(object):    def isHappy(self, n):        """        :type n: int        :rtype: bool        """                if n <=0 :            return False                record = set()                while n not in record:            record.add(n)            sum = 0            while n:                d = n%10                sum += d * d                n /= 10            if sum == 1:                return True            else:                n = sum        return False