"""

202. Happy Number
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.
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.
Return true if n is a happy number, and false if not.

Example 1:

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

Example 2:

Input: n = 2
Output: false

Constraints:

1 <= n <= 231 - 1

"""



class Solution:
    def isHappy(self, n):
        previous_numbers = []
        while n != 1:
            square_sum = 0
            while n > 0:
                digit = n % 10
                square_sum += digit ** 2
                print(f"digit: {digit} n: {n}")
                n //= 10

            if square_sum in previous_numbers:
                return False

            previous_numbers.append(square_sum)
            n = square_sum

        return True

solution = Solution()
print(solution.isHappy(19))
print(solution.isHappy(2))
print(solution.isHappy(21))