Leetcode 202. Happy Number

happy_number.py

def isHappy(n: int) -> bool:
    """
    Leetcode 202. Happy number

    >>> isHappy(7)
    True
    >>> isHappy(19)
    True
    >>> isHappy(2)
    False
    """
    num_lookup = set()

    def sum_squares_digits(n: int) -> int:
        s = 0
        while n:
            n, d = n // 10, n % 10
            s += d ** 2
        return s

    def happy_finder(n: int) -> bool:
        if n in num_lookup:
            return False
        if (s := sum_squares_digits(n)) == 1:
            return True
        num_lookup.add(n)
        return happy_finder(s)

    return happy_finder(n)