Scary 10 part

Question about the task

Under discussion

I need help here definitely! Guys, tell me how far away I am from the solution, and give me some advice because I don't know exactly what the validator wants here. There are so many places to make errors here, and I don't want to bang head against the wall.

Recursion is used when the algorithm for solving the problem is the same as the algorithm for solving part of the problem.
That's just what we have. We need to do a full search of all options and choose the best of them.

Let me remind you of the pattern used to write recursive code:
a) condition for terminating the recursion
b) condition for continuing the recursion (recursive call with a set of parameters from the previous step).
You can always find detailed information online about how to write recursion.

Our current task is to provide a recursive implementation of item 2.2 of the previous task:
(choose a list of available videos that maximizes revenues)
The recursive method must chose the set of commercials that will be displayed to the customer.

This set must meet the following requirements:
1) the amount of money received from impressions should be the maximum of all possible options
2) the total commercial playback time must NOT exceed the cooking time for the current order;
3) a video is shown no more than once for any given order;
4) if several different sets of videos will produce the same amount of money from impressions, then:
4.1) choose the option that maximizes the total time;
4.2) if the total time is the same for multiple such options, then select the option with the smallest number of videos;
5) the number of remaining impressions of any commercial in the set must be positive.

And don't forget to implement item 2.4 of the previous task (display all the relevant videos).

The revalidate() method must be called for each video shown.

Requirements:

The amount of money received from impressions should be the maximum of all possible options.
The total commercial playback time must NOT exceed the cooking time for the current order.
A video should be shown no more than once for any given order.
If there are several different sets of videos that will produce the same amount of money from impressions, then the option with the maximum total time should be selected.
If there are several different sets of videos that will produce the same amount of money and have the same total time, then the option with the minimum number of videos should be chosen.
The set should include only videos with a positive number of remaining impressions.
The revalidate() method must be called for each video shown.

package com.codegym.task.task27.task2712; import com.codegym.task.task27.task2712.kitchen.Cook; import com.codegym.task.task27.task2712.kitchen.Waiter; import java.io.IOException; public class Restaurant { public static void main(String[] args) throws IOException { Tablet tablet = new Tablet(5); Cook cook = new Cook("Amigo"); Waiter waiter = new Waiter(); tablet.addObserver(cook); cook.addObserver(waiter); tablet.createOrder(); } }

Comments (3)

Popular
New
Old

You must be signed in to leave a comment

Thomas

Level 41 , Bayreuth, Germany

21 July 2023, 07:04

useful

I just remember that this was amazingly hard and I had > 30 attempts till it validated. One of my biggest mistakes was that I tried to code the frame first (getting all possible variations) and when that works I wanted to take care of the best set (revenue, play time, ads count). Validation however didn't think the same way as I did and painted a lot of requirements red that I considered to have nothing to do with what wasn't coded. So I continued working on the frame and not the best set. For the recursion.. it needs a lot of info that you need to pass to that method what makes it very complex. So either you have a lot of parameters or you use eg. a holder class or attributes of the containing class. So write a recursive method that gets all combination of active videos and compare each with your best set in the holder class. Make absolutely sure that the above mentioned comparison conditions are checked correctly. This is crucial. And you need a lot of test data for that.

matemate123

Level 50 , Kraków, Poland

23 July 2023, 06:53

Omg, ok I can try :D

matemate123

Level 50 , Kraków, Poland

20 July 2023, 15:12

Edit:

private void displayVideo(int totalCookingTime, List<Advertisement> videos) {
        if (videos.size() < 1 || totalCookingTime < videos.get(0).getDuration()) {
            return;
        }

Change order in if statement to avoid IndexOutOfBoundsException