0202-Happy-Number.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.
'''
class Solution:
    def isHappy(self, n: int) -> bool:
        
        seen = set()
        
        while n != 1:
            
            cur = n
            summ = 0
            
            while cur:
                
                summ += (cur % 10) ** 2
                cur //= 10
                
            if summ in seen:
                
                return False
            
            else:
                
                seen.add(summ)
                n = summ
                
        return True