Re: generate all permutations possible? (twist)

Try this (minimal testing, un-optimized): 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; } michael geary wrote:

Hi Folks, I'm struggling with a permutation problem. I want to take a set of characters (for example "012345678ABCDEF") and generate all permutations of length N, allowing characters to be repeated. For example, I could use this algorithm to generate all HTML hex colors by passing: generatePermutations("012345678ABCDEF",6) Granted, this example would output some 16,777,215 items, but it would be a handy thing. Note that I could get these color values by running from 0 to FFFFFF in hex, but I am looking for something more general so I can play with anagrams, etc. I have seen some algorithms that generate permutations, but I don't want all permutations of "012345678ABCDEF", I just want all 6-digit permutations. I have searched all over for algorithms, and have beat my head against it, but it is just escaping me. Can anyone help? thanks, michael

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