PHP Implementation heap Sequencing

$arr= [9, 43, 12, 0, 87, 1];functionSwap (&$arr,$i,$j){    $tmp=$arr[$i]; $arr[$i] =$arr[$j]; $arr[$j] =$tmp;}//Merge_sort ($arr);functionHeap_sort (&$arr){    $len=Count($arr)-1; $m=intval($len/2); //build a big top pile first     for($i=$m;$i>= 0;$i--) {Heap_adjust ($arr,$i,$len); }    //     for($i=$len;$i> 0;$i--){        Echo"$i"; Swap ($arr, 0,$i); Heap_adjust ($arr, 0,$i-1); }}/** $arr $start+1 to $end is a big top heap, the first element of the new addition, so that this element from the new to become a big top heap*/functionHeap_adjust (&$arr,$start,$end){    if($start>=$end){        return; }    $tmp=$arr[$start]; $i=$start;  for($j= 2 *$start;$j<=$end;$j*=2 ){        if($j+1 <=$end&&$arr[$j+1] >$arr[$j]){            $j++; }        if($arr[$j] <$tmp){             Break; }        $arr[$i] =$arr[$j]; $i=$j; }    $arr[$i] =$tmp;} Heap_sort ($arr);Var_export($arr);

PHP Implementation heap Sequencing