Comments on: Sudoku creator/solver with PHP

By: ??????

?????? — Thu, 22 Dec 2011 12:39:07 +0000

Thank you for this tutorial and i’ll try to develope this code for a facebook application.

By: Emanuele Feronato

Emanuele Feronato — Sat, 11 Jun 2011 07:15:19 +0000

Use as you want. If you are going to making money out of this, consider a small donation to triqui@libero.it

By: Max Kessler

Max Kessler — Sat, 11 Jun 2011 05:28:42 +0000

To clarify, I don’t see a copyright notice in the *script*.

By: Max Kessler

Max Kessler — Thu, 09 Jun 2011 18:06:46 +0000

I don’t see any copyright notice. Did you release this to the public domain? If not, then what are your terms with regard to derivative works?

By: David

David — Wed, 04 May 2011 17:29:49 +0000

Three bugs to fix.

1) The initial array is busted, it is too short.

FIX:

$sudoku = array(
0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0,
0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0,
0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0, 0,0,0
);

2) Initialize the variable $x before the loop within the function “solve”.

$x = 0;

while (!is_solved_sudoku($sudoku)) {
$x++;

3) Check if the array has the key available.

function next_random($possible)
{
$max = 9;

for ($x = 0; $x <= 80; $x++) {
$keyExists = array_key_exists($x, $possible);

if ($keyExists) {
if ( (count($possible[$x]) 0) ) {
$max = count($possible[$x]);
$min_choices = $x;
}
}
}

return $min_choices;
}

By: David

David — Wed, 04 May 2011 17:25:59 +0000

Three bugs:

The initial array is busted, it is too short.

FIX:

In the function “solve”, initialize $x before the loop:

$x = 0;

while (!is_solved_sudoku($sudoku)) {
$x++;

And the big one, check if a key for the array is valid, before trying to access it:

function next_random($possible)
{
$max = 9;

for ($x = 0; $x <= 80; $x++) {
$keyExists = array_key_exists($x, $possible);

if ($keyExists) {
if ( (count($possible[$x]) 0) ) {
$max = count($possible[$x]);
$min_choices = $x;
}
}
}

return $min_choices;
}

Very nice code, works extremely fast.

By: Rizta Husni Ananda

Rizta Husni Ananda — Fri, 08 Apr 2011 14:18:16 +0000

Argh shoot…
Sorry my comment ruin your page. I didn’t know that it would be displayed like that. You can just delete it if you mind.
Btw, on line 157 there’s a bit warning. Some kind of undefined variable. Thank you.

By: Rizta Husni Ananda

Rizta Husni Ananda — Fri, 08 Apr 2011 14:12:40 +0000

For this particular problem (Platinum Blonde from Wikipedia):
$sudoku = array(0,0,0,0,0,0,0,1,2,0,0,0,0,0,0,0,0,3,0,0,2,3,0,0,4,0,0,0,0,1,8,0,0,0,0,5,0,6,0,0,7,0,8,0,0,0,0,0,0,0,9,0,0,0,0,0,8,5,0,0,0,0,0,9,0,0,0,4,0,5,0,0,4,7,0,0,0,6,0,0,0);
And its solution:
839465712
146782953
752391486
391824675
564173829
287659341
628537194
913248567
475916238

My PHP script ran for 6.64 secs in my system. And yours for about 3 times longer.
But still, your way of thinking is really interesting. Very much different than mine. I myself never use array push pop diff etc.
Besides, I already spent over 500 lines of code for the basic elimination, trial & error, backtracking function. But yours only took less than 200 LOC for everything.
Nice and neat. Good one dude!

By: gg

gg — Mon, 21 Feb 2011 15:10:42 +0000

chewdoku is better: try http://twasack.tripod.com/index.htm

By: diallo

diallo — Wed, 09 Feb 2011 10:03:07 +0000

who can send me the sududu(php)