check integer divisible by 3 using hex

divisible-by-3-hex.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2013 KuoE0 <kuoe0.tw@gmail.com>
#
# Distributed under terms of the MIT license.

"""

"""

def add_digits_16_recursion(x):
    if x >= 0x10:
        return add_digits_16(x >> 4) + (x & 0xF)
    return x

def add_digits_16_iteration(x):
    ret = 0
    while x >= 0x10:
        ret = ret + (x & 0xF)
        x = x >> 4
    return ret

def divisible_3(x):
    while x >= 0x10:
        x = add_digits_16_iteration(x)
    return x in [0x0, 0x3, 0x6, 0x9, 0xC, 0xF]

if __name__ == "__main__":
    import sys
    for i in range(int(sys.argv[1])):
        print i, divisible_3(i)