Merge two arrays and sort (HackerRank Task)

merge-arrays-sort.php

<?php

$a = [4, 1, 5, 7, 7, 4, 0, 1, 2, 3];

$b = [5, 2, 4, 5, 9, 9, 5, 0, 1, 2, 3, 4];

$result = $a;

foreach ($b as $el) {
  
  $result[] = $el;  
}

quickSort($result, 0, count($result) - 1);

function quickSort(&$arr, $low, $high) {
        $i = $low;                
        $j = $high;
        $middle = $arr[ ( $low + $high ) / 2 ];  
        do {
            while($arr[$i] < $middle) ++$i; 
            while($arr[$j] > $middle) --$j;  
            if($i <= $j){           
                
                $temp = $arr[$i];
                $arr[$i] = $arr[$j];
                $arr[$j] = $temp;

                $i++; $j--;
            }
        } 
        while($i < $j);
        
        if($low < $j){

          quickSort($arr, $low, $j);
        } 
        if($i < $high){

          quickSort($arr, $i, $high);
        } 
}