<?php
 
function permute($items, $perms = array(), $result = array()) 
{
    if (empty($items)) 
    { 
        $result[] = join('', $perms);
    }  
    else 
    {
        for ($i = 0; $i < count($items); ++$i) 
        {
             $newitems = $items;
             $newperms = $perms;
             $foo = implode(array_splice($newitems, $i, 1));
             array_unshift($newperms, $foo);
             $result = permute($newitems, $newperms, $result);
        }
    }
    return $result;
}
$bar = permute(array("A", 'B', 'C'));
 
var_dump($bar);

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