Straightforward clear solution for The Good Radix by veky - python coding challenges

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Straightforward solution in Clear category for The Good Radix by veky

def checkio(number):
    for base in range(2,37):
        try:
            if not int(number, base)%(base - 1):
                return base
        except ValueError:
            pass
    return 0

#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
    assert checkio("18") == 10, "Simple decimal"
    assert checkio("1010101011") == 2, "Any number is divisible by 1"
    assert checkio("222") == 3, "3rd test"
    assert checkio("A23B") == 14, "It's not a hex"
    print('Local tests done')

Aug. 26, 2013

Comments:

gwie on Nov. 27, 2013, 8:43 p.m.
I guess it is not the fastest solution, but it is simple and easy to read.

veky on Nov. 28, 2013, 7:14 a.m.
It's O(1) (if str is elementary). How fast do you need it to be? :-)

DiEvAl_0d0e0434e59e45f68684d0e on Dec. 22, 2013, 9:27 p.m.
From int() documentation: "If the argument is outside the integer range, the function returns a long object instead". And converting string to long is obviously O(n) ;-) But all other solutions are O(n) too, so yours isn't (asymptotically) slower.

veky on Dec. 23, 2013, 7:16 a.m.
That's why I said "if str is elementary". Of course, if str is elementary, int (what you call "long" here, probably under impression I use Python2) also is. You have to have something as elements of input. If only elementary thing you recognize is a bit, then of course, you're right, it's O(n). But then everything is O(n). + on int is O(n). reading the input itself is O(n). Not very useful. The thing to keep in mind: Python is not C, where you have boxes of fixed size where you put all the information concerning an object you're interested in. Almost everything is dynamically sized (yes, I know about "int" in Py2, but BDFL himself admitted it was a blunder, and corrected it in Py3). In that environment, insisting that complexity analysis be doone in bits is really counterintuitive (at least for me). As I said, the only way to achieve anything lower than linear is either to have trivial types (such as bool) as input, or to ignore (asymptotically) almost all of input. Much more interesting framework is when you consider the virtual machine itself as a computability model. Then one int is one input, and one + of ints is one operation. I hope you understand me. :-)

Thenbacker on Oct. 7, 2016, 12:57 a.m.
Compact and readable, you did it again. I clearly over-complicated things for my first solution. Thanks!

veky on Oct. 7, 2016, 7:45 a.m.
In the meantime, we have got even better batteries in our Python. Check <a href="https://py.checkio.org/mission/good-radix/publications/veky/python-3/the-good-solution/">this one</a>. ;-)

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