用php实现的快速排序

function quickSort(&$arr, $left, $right){
    if($left > $right){
        return $arr;
    }

    $_left = $left;
    $_right = $right;
    $mid = $arr[$_left];

    while($left < $right){
        while($left < $right && $mid <= $arr[$right]){
            $right--;
        }

        while($left < $right && $mid >= $arr[$left]){
            $left++;
        }

        if($left < $right){
            $t = $arr[$right];
            $arr[$right] = $arr[$left];
            $arr[$left] = $t;
        }
    }

    //然后将基准数与$arr[$left]交换位置，即基准数按大小归位
    $arr[$_left] = $arr[$left];
    $arr[$left] = $mid;

    //本次结束，再次分组进行排序
    quickSort($arr, $_left, $left-1);
    quickSort($arr, $right+1, $_right);
}