我想用循环而不是递归函数来编写递归代码。因为递归执行时间太长，甚至会失败。这是使用递归计算二叉树两边的用户数。我想使用循环来完成这个任务。请帮我完成这个任务。提前谢谢。我会非常感谢你的。

function countActiveMembers($mid){
    if ($mid == null) {
        return 0;
    }
    $c = 0;

    include("conn.php");
    $query = $conn->prepare('SELECT leftm, rightm, package_choose FROM member WHERE user_id = ?');
    $query->bind_param('s', $mid);
    $query->execute();
    $query->bind_result($leftm, $rightm, $package_choosen);
    if ($query->fetch()) {
        $query->close();
        $conn->close();

        if ($package_choosen == 1) {
            $c = 0;
        } else {
            $c = 1;
        }

        if (isset($leftm) == false && isset($rightm) == false) {
            return $c;
        }

        if (isset($leftm)) {
            $c = $c + countActiveMembers($leftm);
        }
        if (isset($rightm)) {
            $c = $c + countActiveMembers($rightm);
        }
    } else {
        $query->close();
        $conn->close();
    }
    return $c;
}

    function countLeftActive($mid){
    if ($mid == null) {
        return 0;
    }
    $c = 0;
    include("conn.php");
    $query = $conn->prepare('SELECT leftm, rightm, package_choose FROM member WHERE user_id = ?');
    $query->bind_param('s', $mid);
    $query->execute();
    $query->bind_result($leftm, $rightm, $package_choosen);
    if ($query->fetch()) {
        $query->close();
        $conn->close();

        if (isset($leftm) == false && isset($rightm) == false) {
            return 0;
        }

        if (isset($leftm)) {
            $c = $c + countActiveMembers($leftm);
        }
    } else {
        $query->close();
        $conn->close();
    }
    return $c;
}
function countRightActive($mid){
    if ($mid == null) {
        return 0;
    }
    $c = 0;
    include("conn.php");
    $query = $conn->prepare('SELECT leftm, rightm, package_choose FROM member WHERE user_id = ?');
    $query->bind_param('s', $mid);
    $query->execute();
    $query->bind_result($leftm, $rightm, $package_choosen);
    if ($query->fetch()) {
        $query->close();
        $conn->close();
        if (isset($leftm) == false && isset($rightm) == false) {
            return 0;
        }

        if (isset($rightm)) {
            $c = $c + countActiveMembers($rightm);
        }
    } else {
        $query->close();
        $conn->close();
    }
    return $c;

}