sudoku-solver
A Java application that solves a Sudoku grid after the user enters an initial configuration. This application uses the MVC (model-view-controller) pattern. The GUI has 3 buttons - Solve, Reset and Undo last cell and a status label. The user can input numbers by clicking on cell buttons and pressing Solve. If the initial configuration is invalid (there are duplicate numbers in the same row/column/3x3 grid), the status label will display an error message. The Reset button clears all cells, and the Undo last cell button clears input cells one-by-one, starting from the last input cell.
Algorithm
The Sudoku-solving algorithm follows a backtracking approach:
- Pick an unassigned (empty) cell. If all cells are filled, we're done.
- Find possible candidate numbers for that cell.
- Assign a candidate to that cell and recurse on the remaining grid.
- If the candidate doesn't lead to a valid solution, try the next one.
Test Suite
There are 3 classes with several JUnit tests:
- sudoku/tests/CellTests.java - tests for the Cell class's methods.
- sudoku/tests/GridTests.java - tests for the Grid class's methods.
- sudoku/tests/GameTests.java - test the solving algorithm.
All tests can be run with the sudoku/tests/TestSuite.java class.
Running the application
This repository can be imported as an Eclipse project. The sudoku/driver/Driver.java class can be run to launch the application.
Sample run
- Initial GUI
- Enter values
- Press Solve
External libraries
The application uses the Apache Commons Lang library to check if the user input is not numeric.