Day 2 - Happy number

Solution.py

# https://leetcode.com/explore/featured/card/30-day-leetcoding-challenge/528/week-1/3284/
class Solution:
    def isHappy(self, n: int) -> bool:
        knownNumbers = {}
        
        while True:
            if n == 1:
                return True
            
            if n in knownNumbers:
                return False
            
            knownNumbers[n] = None
            
            n = self.calculateNextNumber(n)
        
        return False
    
    def calculateNextNumber(self, n: int) -> int:
        strDigits = list(str(n))
        return sum((int(digit) * int(digit)) for digit in strDigits)