1 Introduction
Most major websites collect feedback from their customers in order to improve the quality
of their services. The most common form of user feedback is ratings. For example,
[login to view URL] collects users’ ratings of books (see Figure 1), [login to view URL] collects movie
ratings and [login to view URL] gathers users’ rating of hotels.
Figure 1: Some books’ ratings on [login to view URL]
A rating consists mainly of three important pieces of information:
1. The user ID: this is the ID of the user who gave the rating.
2. The item ID: this is the ID of the item being rated. For example, the item can be
a book, a movie or a hotel.
3. The rating value: this is a numerical value that is usually an integer ranging from
1 to 5 (or 1 to 10), where 1 is the lowest rating (user not satisfied) and 5 (or 10) is
the highest rating (user very satisfied).
Your goal in this project is to write a program that reads a list of ratings from a text
file, stores them e!ciently in memory (you should choose the appropriate data structure
for this) and answers a number of queries as e!ciently as possible. Examples of queries
are: What is the rating given by user i to item j? What is the average rating of item j?
What is (are) the highest rated item(s)?
2 Requirements
In this phase, you are required to implement the following classes:
public class Rating {
private int userId;
private int itemId;
private int value; // The value of the rating
// Constructor
public Rating(int userId, int itemId, int value);
// Getters... (No setters. This class is immutable)
}
public class RatingManager {
// Constructor
public RatingManager();
// Read ratings from a file and create a RatingManager object that stores these
ratings
public static RatingManager read(String fileName);
// Add a rating
public void addRating(Rating rating);
// Return all ratings given by user i. Search should be efficient.
public LinkedList<Rating> getUserRatings(int i);
// Return all ratings given to item j. Search should be efficient.
public LinkedList<Rating> getItemRatings(int j);
// Return the average rating of item j. If i has no ratings, -1 is returned
public double getAverageItemRating(int j);
// Return the average rating given by user i. If i has no ratings, -1 is
returned
public double getAverageUserRating(int i);
// Return the list of all items having the highest average rating (for example
if the highest average rating is 4.9, the method should return all items
with average rating 4.9)
public LinkedList<Integer> getHighestRatedItems();
}
Let n denote the number of users, m the number of items and k the number of ratings.
Usually k is much smaller than nm, because a user does not usually rate all items. Your
memory requirement must be O(k) and not O(nm).
3 Deliverable and rules
You must deliver:
1. A report written using the provided template.
We have a team that will definitely provide best solution to you. We do fair code with reasonable price and client satisfaction is our Responsibility. Personally we have 8 + years experience of web, Mobile and desktop based applications and other technology related to this.
Hi, my name is Aleksej
Did I understand correctly - you need only a implementation of the classes from attachment, not whole program yet?
If everything is correct, I can do your task
Hi,
I had hands on experience in Java, SQL server. Knowledge on Data structures and algorithms. I had an experience in java more than 3 years. So, I will complete to fulfill your requirement as soon as possible. Please let me kno
Thanks,
sravani
I believe that I am the best candidate for this position because of my extensive experience as a full stack developer. I was part of the initial development team for VISA payment system migration to the chip based authentication system. Now working with NPCI to build UPI payment system for digital India initiative.