Benchmark of string and numerical approaches to the Happy Number Leetcode task.

happy_number.py

import timeit


def isHappyStr(n: int) -> bool:
    seen = set()
    current = str(n)

    while current not in seen:
        seen.add(current)
        sum = 0
        for digit in current:
            digit = int(digit)
            sum += digit ** 2

        if sum == 1:
            return True
        current = str(sum)
    return False


def isHappyNum(n: int) -> bool:
    seen = set()

    while n not in seen:
        seen.add(n)
        sum = 0

        while n > 0:
            digit = n % 10
            sum += digit * digit
            n //= 10

        if sum == 1:
            return True
    return False


inputs = [1, 11, 15, 25, 42, 69, 100, 128, 256, 123456789]
iterations = 500_000

print(f"Benchmarking {len(inputs)} inputs with {iterations} iterations:\n")

print("isHappyNum:\t", timeit.timeit("[isHappyNum(n) for n in inputs]", globals=locals(), number=iterations))
print("isHappyStr:\t", timeit.timeit("[isHappyStr(n) for n in inputs]", globals=locals(), number=iterations))