Mega Code Archive
Permutation Generator
<![CDATA[
<?
function permutations($letters,$num){
$last = str_repeat($letters{0},$num);
$result = array();
while($last != str_repeat(lastchar($letters),$num)){
$result[] = $last;
$last = char_add($letters,$last,$num-1);
}
$result[] = $last;
return $result;
}
function char_add($digits,$string,$char){
if($string{$char} <> lastchar($digits)){
$string{$char} = $digits{strpos($digits,$string{$char})+1};
return $string;
}else{
$string = changeall($string,$digits{0},$char);
return char_add($digits,$string,$char-1);
}
}
function lastchar($string){
return $string{strlen($string)-1};
}
function changeall($string,$char,$start = 0,$end = 0){
if($end == 0) $end = strlen($string)-1;
for($i=$start;$i<=$end;$i++){
$string{$i} = $char;
}
return $string;
}
?>
To use this Generator you can do something like this :
<?
$Array=permutations("ABC",3);
for($i=0 ; $i < count($Array) ; $i++) {
echo "$i." . $Array[$i] . "<BR>";
}
?>
The output would look like this :
0.AAA
1.AAB
2.AAC
3.ABA
4.ABB
5.ABC
6.ACA
7.ACB
8.ACC
9.BAA
10.BAB
11.BAC
12.BBA
13.BBB
14.BBC
15.BCA
16.BCB
17.BCC
18.CAA
19.CAB
20.CAC
21.CBA
22.CBB
23.CBC
24.CCA
25.CCB
26.CCC
]]>