Question

Hey there I’ve made a recursive permutation function for class, but I output is less than favorable.
http://codepad.org/DOaMP9oc

function permute($arr) {
    $out = array();
    if (count($arr) > 1) {
        $i = 0;
        foreach($arr as $r => $c) {
            $n = $arr;
            unset($n[$r]);
            $out[$c] = permute($n);
        }
    }
    else
        return array_shift($arr);
    return $out;
}

If input is array(1,2,3,4,5), Output is:

Array
(
    [1] => Array
        (
            [2] => Array
                (
                    [3] => Array
                        (
                            [4] => 5
                            [5] => 4
                        )

                    [4] => Array
                        (
                            [3] => 5
                            [5] => 3
                        )

                    [5] => Array
                        (
                            [3] => 4
                            [4] => 3
                        )

                )
ETC......................

This is all Correct, you can read it like this key.key.key.key.value or 12345,12354,12435

Currently, to convert this output to something readable, I’m using this ugly block of code:
http://codepad.org/qyWcRBCl

foreach($out as $k => $a) 
    foreach($a as $l => $b) 
        foreach ($b as $m => $c) 
            foreach ($c as $n => $d) 
                echo $k.$l.$m.$n.$d.'<br>';

How can I alter my function to eliminate the foreach stack and output in a similar format from permute().

Answer 1

I opted to use the following function:

function showPerms($a,$i='') {
    if (is_array($a))
        foreach($a as $k => $v) 
            showPerms($v,$i.$k);
    else 
        echo $i.$a."\n";
}                   

However, I’d still like to do this in a singular recursive function.