202.py

'''
Write an algorithm to determine if a number n 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.

Return True if n is a happy number, and False if not.

Example: 

Input: 19
Output: true
Explanation: 
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 02 = 1
'''

class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        hashSet = set()
        while n != 1:
            curr = n
            sum = 0
            while curr != 0:
                sum +=  (curr % 10) * ( curr % 10)
                curr = curr / 10
            if sum in hashSet:
                return False
            else:
                hashSet.add(sum)
                n = sum
        return True