PHP四种排序算法(快速排序)

$arr = [3, 2, 5, 1, 7, 6];
function quickSort($arr)
{
    $len = count($arr);
    if ($len <= 1) {
        return $arr;
    }
    $mid = $arr[0];
    $left = $right = [];
    for ($i = 1; $i < $len; $i++) {
        if ($arr[$i] > $mid) {
            $right[] = $arr[$i];
        } else {
            $left[] = $arr[$i];
        }
    }
    $left = quickSort($left);
    $right = quickSort($right);

    return array_merge($left, [$mid], $right);
}


var_dump(quickSort($arr));