Sudoku solver

[Seymore4Head]

On Sun, 29 Mar 2015 23:17:23 +0100, BartC <bc at freeuk.com> wrote:

>On 29/03/2015 22:21, Mark Lawrence wrote:
>> On 28/03/2015 23:50, BartC wrote:
>>> On 28/03/2015 03:39, Sayth wrote:
>>>> Good test for pypy to see where it's speed sits between C and Python.
>
>>> Python 3.1:     1700 seconds     (normal Python interpreter)
>>> PyPy:           93 seconds
>>> C unoptimised:  17 seconds       (gcc -O0 32-bit)
>>> C optimised:    3.3 seconds      (gcc -O3 32-bit)
>
>> https://attractivechaos.wordpress.com/2011/06/19/an-incomplete-review-of-sudoku-solver-implementations/
>
>"The fastest Sudoku solver can solve even the hardest Sudoku in about 1 
>millisecond and solve most others in 0.1 millisecond."
>
>Blimey, we might as well pack up and go home then!
>
>Actually I didn't realise people took these things so seriously. I came 
>into the thread when I thought it was being suggested that brute-force 
>approaches to this problem were not viable.
>
>I think to be useful, it needs to work in a reasonable amount of time, 
>and a few seconds would be more than reasonable; it doesn't need to be 
>100 microseconds. Unless somehow somebody's got millions of the things 
>to get through.
>
>But I guess people aren't interested in actually solving the daily 
>sudoku in the paper** (that would be very dull); maybe there is more 
>sport in finding a faster machine solution than anyone else.
>
The technical term for that is "a pissing contest"

>(I'm more interested now in getting my own dynamic language to compete 
>with PyPy, and in getting own static language to compete with C/gcc, as 
>the timing for this benchmark was pretty bad.)
>
>(** Although I did come across a prize 16x16 sudoku in the paper a few 
>years back. I adapted my code to 16x16 in 10 minutes or so, which took a 
>further couple of minutes to solve the given puzzle, and sent it in. But 
>I didn't win...)