PHP algorithm quick sort

The content introduced in this article is the quick sort code in the PHP algorithm. Now I share it with you. Friends in need can also refer to it. Let’s take a look together.

<?php

//快速排序

function quicksort($arr)
{
   //结束条件
   //判断当前数组是否需要排序
    if(count($arr)<=1){
        return $arr;
    }

    $num = $arr[0]; //进行排序 定义标尺

    $left_array = []; //左边数组
    $right_array = [];//右边数组 
    for($i = 1;$i<count($arr);$i++){
        
        if($num>$arr[$i]){

            $left_array[] = $arr[$i];//比当前数小放到左边数组

        }
        else
        {

            $right_array[] = $arr[$i];//比当前数大放到右边数组
        }
          
    }
    //递归 调用自身
     $left_array = quicksort($left_array);
     $reght_array = quicksort($right_array);
    //合并数组 返回排序好的数组
    return array_merge($left_array,array($num),$reght_array);
}
//需要排序的数组
$arr = array(2,3,5,6,9,8,4,1);

//调用递归
print_r(quicksort($arr));

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