php实现快速排序

<?php
/**
* Created by PhpStorm.
* User: Administrator
* Date: 16-8-29
* Time: ����3:02
*
* ��������
*
*/

function quick_sort($arr){

$length = count($arr);
if($length<=1){
return $arr;
}

$base_num=$arr[0];

$left_array=array();
$right_array=array();

for($i=1; $i<$length; $i++){
if($base_num>$arr[$i])
$left_array[]=$arr[$i];
else
$right_array[]=$arr[$i];
}

$left_array=quick_sort($left_array);
$right_array=quick_sort($right_array);

return array_merge($left_array, array($base_num), $right_array);

}

$arr=array(23,50,60,31,68,90,15,18,51,10);

$arr=quick_sort($arr);

var_dump($arr);