php recursive function return array

Question

Here is the original function (recursive function):

function permute($items, $perms = array()) 
{
 if (empty($items)) 
 { 
 echo join('', $perms).'<br>';
 } 
 else 
 {
 for ($i = 0; $i < count($items); ++$i) 
 {
 $newitems = $items;
 $newperms = $perms;
 $foo = implode(array_splice($newitems, $i, 1));
 array_unshift($newperms, $foo);
 permute($newitems, $newperms);
 }
 }
}
permute(array("A", 'B', 'C'));

In this case, the output will be:

cba
bca
cab
acb
bac
abc

How to modify this part:

if (empty($items)) 
{ 
 echo join('', $perms).'<br>';
} 

change it to return array of string instead of directly echo in the function?

Answer 1

Try this (IdeOne example):

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);

• mickmackusa: This answer is missing its educational explanation.