Sudoku Explainer

Current version: 1.2.1

The Sudoku Explainer is a Sudoku solver written in Java. It explains how to solve any sudoku puzzle in an interactive way: give it a sudoku that has a unique solution, and it will solve it step by step. At each step, a description of the technique that is used, with a graphical illustration, is given.

Download the Sudoku Explainer Requirements Comments
SudokuExplainer.jar Java Runtime version 5 or greater This version is a JAR (Java archive) executable file Windows 98/Me/NT/XP/2000/2003 or below This version is a double-clickable Windows application. Note that it is bundled with a JRE within the application's directory. This JRE is used by the Sudoku Explainer only. It does not affect any system files or other Java installations at all. JDK >= 5.0 Java source code, available under the terms of the LGPL open source license

If your browser supports Java 5, you can also launch the application from an applet using the following button:

Some features of the Sudoku Explainer:
  • Allows you to enter any sudoku puzzle, including partially solved ones.
  • Solves the sudoku puzzle step by step, by the mean of a "Solve Step" button
  • Gives an explanation of the technique that is used at each step, with a graphical illustration. Even the most complex techniques, when required, are illustrated and explained
  • Automatically displays and updates all the possible values for cells that are still empty
  • Can display cells as A1 - I9 (friendly) or R1C1 - R9C9 (traditional).
  • Always chooses the simplest solving technique that can be applied
  • Also allows you to get all the hints that are applicable at any stage, and to browse them (see screenshot on the right)
  • Allows you to check the validity of a sudoku puzzle (whether it has a unique solution). Note that the Sudoku Explainer will not solve sudoku puzzles with more than one solution.
  • Allows you to edit the candidates in empty cells
  • Multiple Look & Feels (Usually: System standard, CDE/Motif and Java/Metal)
  • Implements the following solving techniques:
    • Naked Singles and Hidden Singles
    • Direct Pointing, Claiming and Hidden Pairs
    • Naked and Hidden Pairs, Triplets and Quads
    • Locking, Claiming (intersections), X-Wing, Swordfish and Jellyfish
    • XY-Wing and XYZ-Wing
    • Unique Rectangles and Loops
    • Bivalue Universal Grave
    • Aligned Pair Exclusion
    • Bidirectional Cycles
    • Nishio
    • Forcing Chains
  • Never uses brute-force
Screenshot of the Sudoku Explainer
Screenshot of the Sudoku Explainer (click to view full size version)

Related pages

Some interesting Sudokus for exploring the solving techniques
Sudoku Explainer FAQ
Equivalence between Naked Sets, Hidden Sets and Fishy patterns
Sudoku on Wikipedia - The free encyclopedia
Sudoku Susser - another Sudoku solver
Sudoku Assistant/Solver - another Sudoku solver (in Javascript)
Sudoku Players' Forums
Sudoku Programmers' Forums

Last update: 2007-12-28