題目

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

代碼

class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if n <= 0:
            return False
        nums = set([n])
        while n != 1:
            t = 0
            while n != 0:
                t += (n%10) ** 2
                n /= 10
            n = t
            if n in nums:
                return False
            else:
                nums.add(n)
        return True