Generating an efficient permutation without the single result [duplicate] - php

Question

This question already has answers here:
Get all permutations of a PHP array?
(7 answers)
Closed 6 months ago.
Is there any way I could pull something like this when I call the function:
perm(array("one", "two", "tree"));
that would result to:
Array ( [0] => one [1] => two )
Array ( [0] => one [1] => tree )
Array ( [0] => two [1] => one )
Array ( [0] => two [1] => tree )
Array ( [0] => tree [1] => one )
Array ( [0] => tree [1] => two )
Array ( [0] => one [1] => two [2] => tree )
Array ( [0] => two [1] => one [2] => tree )
Array ( [0] => one [1] => tree [2] => two )
Array ( [0] => tree [1] => one [2] => two )
Array ( [0] => two [1] => tree [2] => one )
Array ( [0] => tree [1] => two [2] => one )
The problem is the array is dynamic and the value could become something like perm(array("one", "two", "tree", "five","8"));
I wanted to generate all the permutation even if the it becomes.
perm(array("one", "two")); or perm(array("two", "tree", "five","8"));
The problem of what I have below is that it starts from 1 permutation instead of 2 permutation above.
</php
function perm($arr, $temp_string, &$collect) {
if ($temp_string != "")
$collect []= $temp_string;
for ($i=0, $iMax = sizeof($arr); $i < $iMax; $i++) {
$arrcopy = $arr;
$elem = array_splice($arrcopy, $i, 1);
if (sizeof($arrcopy) > 0) {
perm($arrcopy, $temp_string ." " . $elem[0], $collect);
} else {
$collect []= $temp_string. " " . $elem[0];
}
}
}
?>

Answer 1

This may not have the same order but this is the same result you are expecting. You just have to add another if condition. I am assuming someone smarter than me here could recreate your function to make it more efficient with lower benchmarks. Otherwise you would have to go for this:
$collect = array();
function permute($arr, $temp_string, &$collect){
for($i=0, $iMax = sizeof($arr); $i < $iMax; $i++){
$arrcopy = $arr;
$elem = array_splice($arrcopy, $i, 1);
$jval = $temp_string." ".$elem[0];
if(!empty($temp_string)){
$collect [] = explode(" ",$jval);
}
if(sizeof($arrcopy) > 0){
permute($arrcopy, $jval, $collect);
}
}
}
permute(array('one', 'two', 'tree'), "", $collect);
Would result to:
Array ( [0] => [1] => one [2] => two )
Array ( [0] => [1] => one [2] => two [3] => tree )
Array ( [0] => [1] => one [2] => tree )
Array ( [0] => [1] => one [2] => tree [3] => two )
Array ( [0] => [1] => two [2] => one )
Array ( [0] => [1] => two [2] => one [3] => tree )
Array ( [0] => [1] => two [2] => tree )
Array ( [0] => [1] => two [2] => tree [3] => one )
Array ( [0] => [1] => tree [2] => one )
Array ( [0] => [1] => tree [2] => one [3] => two )
Array ( [0] => [1] => tree [2] => two )
Array ( [0] => [1] => tree [2] => two [3] => one )