array sorting custom algorithm using (PHP) - php

Question

http://sandbox.onlinephpfunctions.com/code/971f4a6c9dfe80ec6277dd89653ea160af3c68e4
I can't find solution .. Please, help to return changed array
Code
<?php
function bell_sort($arr, $head, $tail, $queue) {
if($head != $tail){
$min = $arr[$head];
$min_index = $head;
for($i = $head; $i <= $tail; ++$i){
if($arr[$i] < $min){
$min = $arr[$i];
$min_index = $i;
}
}
if($queue){
$tmp = $arr[$head];
$arr[$head] = $arr[$min_index];
$arr[$min_index] = $tmp;
$head++;
}else{
$tmp = $arr[$tail];
$arr[$tail] = $arr[$min_index];
$arr[$min_index] = $tmp;
$tail--;
}
bell_sort($arr, $head, $tail, !$queue);
}else{
return $arr;
}
}
$n = 10;
for($i = 0; $i < $n; ++$i){
$arr[$i] = rand(0, 100);
}
$head = 0;
$tail = count($arr) - 1;
$queue = 1;
$new_arr = bell_sort($arr, $head, $tail, $queue);
var_dump($new_arr);

Answer 1

You're missing a return statement in one of the recursive paths in the bell_sort function.
if($queue){
$tmp = $arr[$head];
$arr[$head] = $arr[$min_index];
$arr[$min_index] = $tmp;
$head++;
}else{
$tmp = $arr[$tail];
$arr[$tail] = $arr[$min_index];
$arr[$min_index] = $tmp;
$tail--;
}
bell_sort($arr, $head, $tail, !$queue);
Change the line above line to
return bell_sort($arr, $head, $tail, !$queue);
and it will work