A robust terminal-based Sudoku application built with modern C++ that can both solve existing puzzles and generate fresh challenges. The project showcases clean object-oriented design, defensive error handling, and flexible algorithms suitable for extension.

• Two Play Modes: Load puzzles from text files or generate new boards with selectable difficulty.
• Recursive Backtracking Solver: Efficiently fills the grid while respecting row, column, and sub-grid constraints.
• Puzzle Generation: Creates randomized puzzles by removing cells from a solved board using a Mersenne Twister RNG.
• Encapsulated OOP Design: The Sudoku class owns the grid, solver, validation, and generator logic to keep the interface tidy.
• Robust Error Handling: Graceful messaging for invalid files or unexpected input, preventing undefined states.
• Interactive CLI Menu: Simple navigation loop with input validation and cross-platform screen clearing.

• C++11-compatible compiler (tested with g++ on macOS)
• Standard C++ library only; no external dependencies

1. Clone the repository:

   git clone https://github.com/zisshh/sudoku-solver-CLI.git
   cd sudoku-solver-CLI

2. Compile the project:

   g++ -std=c++11 -o sudoku main.cpp Sudoku.cpp

3. Run the executable:

   ./sudoku

4. Solve or Generate:
   • Choose option 1 to solve a puzzle from a file such as puzzle.txt (9x9 grid, zeros for blanks).
   • Choose option 2 to generate an Easy, Medium, or Hard puzzle on the fly.

├── main.cpp        # Menu-driven CLI entry point
├── Sudoku.h        # Sudoku class interface and Grid type alias
├── Sudoku.cpp      # Solver, validation, and puzzle generation implementation
├── puzzle.txt      # Sample puzzle input (zeros are empty cells)
└── log.txt         # Optional log/output file (if used during development)

• Const-Correct Interfaces: Read-only helpers are marked const to enforce immutability where possible.
• Helper Encapsulation: Internal checks like isSafe remain private to the Sudoku class, keeping the API lean.
• RAII-Friendly Constructors: Objects initialize their board state on construction, preventing partially built puzzles.
• Standard Library First: Uses std::vector, <random>, and <limits> for portable, dependable behavior.

• Difficulty calibration via advanced heuristics or constraint propagation.
• Exporting generated puzzles to files for later replay.
• Optional GUI front end or web assembly port for broader reach.

This project is released under the MIT License. See LICENSE for details.