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.

Example: 

Input: 19
Output: true
Explanation: 
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Python

 
class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        temp_list= []
        result = self._add(n)
        while result not in temp_list:
            temp_list.append(result)
            result = self._add(result)
            if result == 1:
                return True
        return False

    def _add(self, num):
        result = 0
        for i in str(num):
            result += int(i)**2
        return result