Happy Number.py

"""
Problem: 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
"""

class Solution:
    def isHappy(self, n: int) -> bool:
        sum1 = 0
        os = set()
        while(n is not 1):
            if(n in os):
                return False
            os.add(n)
            st = str(n)
            sum1 = 0
            for i in range(len(st)):
                sum1 = int(st[i])**2 + sum1
            n = sum1
        return True