constraint based killer sudoku solver performance improvements

[Blockheads Oi Oi]

On 27/01/2012 06:57, Frank Millman wrote:
>
> "Blockheads Oi Oi"<breamoreboy at yahoo.co.uk>  wrote:
>
>> I have a working program based on [1] that sets up all different
>> constraints for each row, column and box and then sets exact sum
>> constraints for each cage.  It'll run in around 0.2 secs for a simple
>> problem, but a tough one takes 2 hours 45 minutes.  I did some research
>> into improving the performance and found [2] but can't work out how to
>> implement the constraints given.  Can someone please help, assuming that
>> it's even possible.
>>
>> [1] http://pypi.python.org/pypi/python-constraint/1.1
>> [2] http://4c.ucc.ie/~hsimonis/sudoku.pdf
>
> I don't have an answer, but are you aware of this -
>
> http://www.ics.uci.edu/~eppstein/PADS/Sudoku.py
>
> It is a sudoko solver written in pure python.
>
> I don't know what you call a tough problem, but this one solves the hardest
> one I have thrown at it in the blink of an eye. It also outputs a full trace
> of  the reasoning it used to arrive at a solution.
>
> Frank Millman
>

I'd looked at this years back and forgotten all about it so thanks for 
the reminder :)  Some of the code names directly match ideas given in my 
[2] above so I'll take another look.
-- 
Cheers.

Mark Lawrence.