<?php
// Returns the total number of $count-length strings generatable from $letters.
function getPermCount($letters, $count)
{
$result = 1;
// k characters from a set of n has n!/(n-k)! possible combinations
for($i = strlen($letters) - $count + 1; $i <= strlen($letters); $i++) {
$result *= $i;
}
return $result;
}
// Decodes $index to a $count-length string from $letters, no repeat chars.
function getPerm($letters, $count, $index)
{
$result = array();
for($i = 0; $i < $count; $i++)
{
$pos = $index % strlen($letters);
$result[] = $letters[$pos];
$index = ($index-$pos)/strlen($letters);
$letters = substr($letters, 0, $pos) . substr($letters, $pos+1);
}
sort($result);
return implode("", $result);
}
$r = array();
//$letters = 'abcdefghijklm';
$letters = 'abc';
$len = strlen($letters);
for ($c = 0; $c < $len; $c++)
for($i = 0; $i < getPermCount($letters, $c); $i++)
$r[] = getPerm($letters, $c, $i);
print_r(array_unique($r, SORT_REGULAR));
- Output for 5.2.9 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
- Array
(
[0] =>
[1] => a
[2] => b
[3] => c
[4] => ab
[6] => ac
[8] => bc
)
- Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.8
- Warning: Wrong parameter count for array_unique() in /in/Vtkpn on line 37
preferences:
319.46 ms | 402 KiB | 459 Q