Implement Difficulty Extraction Feature

Description

The sudoku_solver_rs library currently supports solving and generating Sudoku puzzles. The next step is to implement a feature that can extract the difficulty level of a given Sudoku puzzle.

Requirements

• The feature should be able to analyze a given Sudoku puzzle and determine its difficulty level.
• The difficulty level could be categorized into various levels such as 'Easy', 'Medium', 'Hard', and 'Expert'.
• The feature should be robust and accurate, providing a reliable difficulty level for any valid Sudoku puzzle.

Potential Challenges

• Determining the criteria for each difficulty level.
• Ensuring the feature works efficiently for large and complex puzzles.

Additional Information

This feature will enhance the functionality of the sudoku_solver_rs library and provide more insights about the Sudoku puzzles to the users.