Recommender Systems by User-based Collaborative Filtering

[ngtduc693]

This PR introduces a User-based Collaborative Filtering algorithm implemented in C#. The algorithm predicts a user's rating for a given item based on ratings from other users with similar preferences. The main components of this PR include

CollaborativeFiltering included:

• CalculateSimilarity: Computes the similarity between two users based on their shared item ratings using the Pearson correlation coefficient.

• PredictRating: Using ratings from other users who have rated the same item, it forecasts a target user's rating for a particular item. The prediction is a weighted sum determined by user similarity.

• I have performed a self-review of my code

• My code follows the style guidelines of this project

• I have added tests that prove my fix is effective or that my feature works

• New and existing unit tests pass locally with my changes

• Comments in areas I changed are up to date

• I have added comments to hard-to-understand areas of my code

• I have made corresponding changes to the README.md

[ngtduc693]

First time attending hacktoberfest 2024, and this is my first PR, I hope everything goes well 😃