Re: Sudoku

Date	2013-03-29 18:11 -0400
From	Dave Angel <davea@davea.name>
Subject	Re: Sudoku
References	(2 earlier) <5ce10a13-be58-4548-85df-e1d865d3304e@googlegroups.com> <mailman.3857.1364445382.2939.python-list@python.org> <f160e316-e2f6-4314-827e-9d48007f7f70@googlegroups.com> <mailman.3946.1364556269.2939.python-list@python.org> <17da5afc-7a9b-40ea-a544-6012dfeef3ce@googlegroups.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.3970.1364595086.2939.python-list@python.org> (permalink)

Show all headers | View raw

On 03/29/2013 05:47 PM, Eric Parry wrote:
>
>>   <SNIP>
>>
> That explains why the program keeps running after a solution is found.

A recursive function can be designed to find all solutions, in which 
case it would (as you say) keep running.

The function you posted in the first place uses exit() to avoid keeping 
running.  It stops as soon as a solution is found.

Sometimes a problem cannot be solved in the number of stack entries 
supplied by Python.  So even though such a function will terminate, it 
may crash first if the problem is too big.  Example, the factorial 
problem I described earlier, if you pass it 2000 as a parameter.  If 
this is a problem, one can tell the Python to give you more stack entries.

Given a 9x9 matrix, and at least some of them filled in, the maximum 
depth your code can use is less than 81.  So it won't get a stack 
overflow in any implementation of Python I've seen.  Perhaps in an 8051.

Sometimes a bug in such a function will cause it to run indefinitely, 
and/or to overflow the stack.  I don't see such a bug in this function.

-- 
DaveA

Thread

Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-26 22:44 -0700
  Re: Sudoku Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-03-27 08:58 +0100
    Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-27 20:00 -0700
      Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-28 00:36 -0400
        Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-28 15:11 -0700
          Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-28 19:28 -0400
            Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-28 22:07 -0700
            Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-28 22:07 -0700
          Re: Sudoku Chris Angelico <rosuav@gmail.com> - 2013-03-29 09:45 +1100
            Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-29 14:47 -0700
              Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-29 18:11 -0400
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-30 15:06 -0700
                Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-30 19:15 -0400
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-31 15:03 -0700
                Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-31 18:34 -0400
                Re: Sudoku Arnaud Delobelle <arnodel@gmail.com> - 2013-03-31 23:59 +0100
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-31 15:03 -0700
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-31 15:27 -0700
                Re: Sudoku Chris Angelico <rosuav@gmail.com> - 2013-04-01 09:35 +1100
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-31 20:58 -0700
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-31 15:27 -0700
                Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-30 15:06 -0700
            Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-29 14:47 -0700
        Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-28 15:11 -0700
  Re: Sudoku Damien Wyart <damien.wyart@free.fr> - 2013-03-27 09:49 +0100
  Re: Sudoku Dave Angel <davea@davea.name> - 2013-03-27 05:38 -0400
  Re: Sudoku Eric Parry <joan4eric@gmail.com> - 2013-03-27 19:49 -0700

csiph-web