On 29/03/2015 13:01, BartC wrote:
On 29/03/2015 11:35, Steven D'Aprano wrote:
Anyway, we don't really know where the confusion lies. Perhaps the
description is misleading, or I'm just confused, or Bart's idea of brute
force is not the same as my idea of brute force, or perhaps he really
is a
super-genius who has casually relegated C to the dust bin of historic
languages...
My solver definitely works, as the solutions produced by the two
algorithms are identical.
I'm not clever enough to produce a properly analytical solver, but
perhaps it is not quite as brute force as the Python one.
I've looked at my code and I don't really understand it (it's from a
long time ago), and it would take quite a while to convert it to Python
and post it. (Most of it seems to be preoccupied with multiple ways of
indexing the board or grid.)
(If it's of any interest, this non-Python code is here:
http://pastebin.com/5cXd2Pef )
I've managed to create a Python version of my 'brute force' sudoku solver:
http://pastebin.com/CKmHmBKm
It was hard going as I don't normally write Python. But it worked
practically first time, after building it bottom-up and then putting the
solvepuzzle() routine in place.
The data for the 'hard' puzzle is hard-coded into it, so you just run it.
Python 3.1 (normal CPython) took 13 or 14 seconds to solve (previously
1700 seconds with the OP's code).
PyPy took 1.3 seconds (previously 93 seconds). (Annoyingly, faster than
the 1.7 seconds of my language...)
(The original code in my language that I posted has been simplified -
which also made it faster, and the Python code was based on that
version. The Pastebin code has been updated.)
I won't bother to test a C version of this, as it's a bit more awkward
to translate (making use of strings and deep copies of arrays).
--
Bartc
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