hotel-booking | Our project with databases | Reactive Programming library

I just installed a plugin to my word-press site and now I'm getting this message:

Fatal error: Can't use method return value in write context in /home2/royaldlx/public_html/wp-content/plugins/motopress-hotel-booking-lite/includes/admin/manage-cpt-pages/booking-manage-cpt-page.php on line 194

What had happened? is there any way to fix it? Thank you in advance. Below the code:

I try to execute the Maven goal to build and run Apache Tapestry 5.4.x locally but it always failed:

Ideas I tried:

1. IntelliJ official Plugin arch type
2. Getting started from tapestry.org
3. Hotel booking example from GitHub.

Maven / Java version

i downloaded a plugin in wordpress called WP Hotel Booking using Divi Theme Builder.

This is his actual design in my site:

How can i align these elements side by side like this?

I guess the problem is since its a wordpress theme and i didnt created that one, i can only use css to try do these changes.

This is the actual website if needed to try with console: http://198.199.66.183/ (yep, no domain yet) These are the css class:

I am fairly new to Wordpress but I do understand child themes.
This is the first time I came across a theme with a plugin that has its own style sheet enqueued. Is the following code adding the stylesheet of the booking plugin into the main parent style sheet already (so I do not need to include this in the child theme), or is this an additional enqueued style sheet and I will have to also include that separately in my child's theme.

Any explanation as to what exactly and how this code is working with the parent style would be appreciated. Wordpress codex is practically useless in this area.

A hotel manager has to process N advance bookings of rooms for the next season. His hotel has K rooms. Bookings contain an arrival date and a departure date. He wants to find out whether there are enough rooms in the hotel to satisfy the demand. Write a program that solves this problem in time O(N log N).

Input:
First list for arrival time of booking.
Second list for departure time of booking.
Third is K which denotes count of rooms.

Returns:
true if there are enough rooms for N booking
false if there are not enough rooms for N booking

My approach:
Heapsort arrive list, applying same changes to depart to maintain index relationship. A TreeSet is used to track next checkout time. For each iteration: a guest is checked in and checkout time is added to TreeSet. If a checkout has occurred, a guest is removed and next checkout is polled from TreeSet. If overbooking ever occurs, false is returned.

My solution works on NetBeans but fails when I run it through the website. Any help will be very much appreciated.
Original question: https://www.interviewbit.com/problems/hotel-bookings-possible/

I want to send email through contact form from a website. And I have given link to php file in which senders mail is there and I'm using mail() function by passing arguments when I hits submit button the following error is displaying like this.

Warning: mail(): Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in E:\xampp\htdocs\hotel-booking\contact_process.php on line 52

Why?