The Java Sudoku Game

by Mike Reynolds

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Introduction


A Sudoku game board is comprised of a nine by nine grid of game squares, so that it has nine rows and nine columns. The board is divided up into nine three by three boxes or mini-grids, each of which contains nine game squares.

Initially for a Sudoku game or puzzle some of the game squares will contain digits. The challenge for the user is to add digits to the empty game squares such that when all game squares have been filled, all digits from one to nine will be found in each row, column, and box or mini-grid.

The Java Sudoku Applet

To start the game just click on the "Start Sudoku Game" button, at the left.

The Sudoku applet version of the game allows the user to enter a sudoku puzzle from a book or newspaper, and solve it. Select the Help / Help Topics menu item for more information on puzzle entry.

The applet can check whether the puzzle entered is valid, i.e. has a unique solution, if the Game / Validity Check menu item is selected.

With the game running, you will need to click on the gameboard before using letter shorcuts, such as "A" below, so that the board is in focus.

The applet can make the next play for the user, if the Game / Next Play menu item is selected, or "A" is typed.

The applet can solve the entire puzzle for the user, if the Game / Solve Puzzle menu item is selected.

The applet supports "writing" which is when the user jots down numbers for some empty game squares, to help remember either digits that may be there or may not be there, depending on the user's strategy or method. Select the Writing / Enable Writing item to turn on writing, and then when you enter a digit it toggles that writing digit alternately on or off.

And of course the applet may act as tutor by giving the user a hint as to what the next play may be. It reveals the logic by which it found the play, by displaying graphical symbols on the game board (more details below). Just select the Game / Hint menu item, or type the letter H, to get the hint.

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