RE: [PHP] Generate every possible combination
| From: | Lance Lovette | Date: | Fri, 17 May 2002 02:27:53 +0000 |
| Subject: | RE: [PHP] Generate every possible combination | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-98000@lists.php.net to get a copy of this message | ||
Here's the function I use:
// array array_permute(array [, string])
//
// Returns an array containing the permutations of the values in an array.
//
// Example:
// $a = array(1, 2, 3);
// $p = array_permute($a)
//
// Result:
// p[0] = '1,2,3'
// p[1] = '1,3,2'
// p[2] = '2,1,3'
// p[3] = '2,3,1'
// p[4] = '3,2,1'
// p[5] = '3,1,2'
//
function array_permute(&$a, $glue = ',')
{
$retval = array();
array_permute_internal($a, $glue, $retval, 0, count($a));
return $retval;
}
// Private function used by array_permute.
function array_permute_internal(&$a, $glue, &$retval, $depth, $ubound)
{
if ($ubound > 0)
{
for ($i=0; $i < $ubound; $i++)
{
$c = $a[$depth+$i];
$a[$depth+$i] = $a[$depth];
$a[$depth] = $c;
array_permute_internal($a, $glue, $retval, $depth+1, $ubound-1);
$c = $a[$depth+$i];
$a[$depth+$i] = $a[$depth];
$a[$depth] = $c;
}
}
else
{
$retval[] = implode($glue, $a);
}
}
-----Original Message-----
From: Evan Nemerson [mailto:evan@coeus-group.com]
Sent: Thursday, May 16, 2002 12:17 AM
To: php-general@lists.php.net
Subject: [PHP] Generate every possible combination
I need to generate every possible combination of the the values in an array.
For example, if...
$array = Array("A", "B", "C");
I want to be able to do something like
print_r(magic_function($array));
which would output
Array
(
[0] => "ABC"
[1] => "ACB"
[2] => "BAC"
[3] => "BCA"
[4] => "CAB"
[5] => "CBA"
)
I really have no idea where to begin. The best lead I can think of is that
there are going to be n! elements in the output array, where n is the size
of
the input array.
Any help would be greatly appreciated.
Evan
--
Think not those faithful who praise all thy words and actions, but those who
kindly reprove thy faults.
Socrates
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