Sudoku Solver Help

How to play Sudoku
The Sudoku craze is sweeping the nation! The are about a million books (195 at Amazon) on Sudoku. Buy one. Recommendations on where to buy Sudoku books: a place that sells books.

How to use the Sudoku Solver

The Display
(This text pertains to the standard 9x9 puzzle size. For a description of the 12x12 or 16x16 puzzle displays, do the math.)
81 tiles are arranged in 9 rows and 9 columns, and are divided into 9 squares. Contained within each tile are 9 candidates.

Clicking on a candidate number will erase all of the candidates in that tile and insert the selected number. It will also erase candidates of the same number in the same row, column, and square as the tile you clicked. (Note: The automatic erasure of candidates will be disabled if "Pltboi Option (No Help)" is selected in the General Preferences).

Holding the Shift key while clicking a candidate will erase only the candidate you click.
Holding the Alt key while clicking a candidate will change the color of the candidate. Repeated Alt-clicks will cycle through several, (8 I think), colors sequentially.
Holding the Alt and Shift keys while clicking a candidate will change the color of all candidates of the same number. Repeated Alt-Shift-clicks will cycle through several, (8 I think), colors sequentially.

The Buttons

Difficulty Button

The Difficulty button appears only for 9x9 or 16x16 puzzles. Choose the level of difficulty of the puzzle to generate with the New button. The following guide will tell you which puzzle solving techniques are required for each level of difficulty:
For excellent descriptions and examples of all these solving techniques (and more!) go to SadMan Software: Techniques for Solving Sudoku

	Easy	Medium	Hard	Extreme
Naked Single	X	X	X	X
Hidden Single	X	X	X	X
Block to Col/Row		X	X	X
Block to Block		X	X	X
Naked Subset			X	X
Hidden Subset			X	X
X-Wing			X	X
Guessing				X

New Button
The New button will generate a new Sudoku puzzle (9x9 and 16x16 only) for you to enjoy. The difficulty of the generated puzzle will be determined by the setting of the Difficulty button.
The generation of a new puzzle will take anywhere from 10 to 15 seconds on fast machines. On a real dinosaur it could be longer, so be patient.
If the New button is missing, it is because you have a board size of 12x12 selected.
If you select a new game with an old game unfinished, you will be treated to an annoying pop-up warning you. If you never want to see the warning again, choose the appropriate rude response.

Undo Button
The Undo button will reverse the action of your last click, except for color (Alt-click) clicks. If the Undo button is "grayed out" there are no more actions to undo. Holding down the Alt key when clicking the Undo button will undo everything that has been done. To clear the undo list, (and create a new "starting place"), right-click on the Undo button and select "CLEAR UNDO LIST" from the menu. The keyboard combination of Shift-Ctrl-Z is a shortcut for the Undo button.

Hint Button
The Hint button will reveal a logical place to select or erase a candidate. Candidates that can be selected will be colored RED. Candidates that can be erased will be colored YELLOW. Sometimes, several candidates can be erased for the same hint. Messages below the buttons tell which solving technique was used in finding the hint and link to the Sadman Software page that describes the technique in detail. This is all the Hint button will do unless there is some Undocumented Easter Egg feature that I have not told you about (wink, wink). Note: The Hint button will be grayed out when "Pltboi Option (No Help)" is selected in the Preferences.

Reset Button
The Reset button will return the display to its initial setup. To use the Reset button, click once to open the Lid and then click again to reset the puzzle. Clicking the Lid before reseting the puzzle will close the Lid.

Minimize Button
The Minimize button will reduce the puzzle board to the size of a minimize button. To restore the board, click the Restore Button.

Restore Button
The Restore button (not pictured) looks a lot like the Minimize Button, but with the chevrons pointing up instead of down. Clicking the Restore button will restore the puzzle board to its last size and position. To move the Restore button around your desktop, hold down the CTRL button when you click on it.
The next time you use the Minimize button, the Restore button will be where you last left it, so try not to lose it. If you do happen to misplace your Restore button, (it is awfully tiny), you can restore the puzzle by selecting "Sudoku Solver" from the list of current widgets available through the Yahoo! Widget Engine icon in the system tray. After the puzzle is restored, right-click on the Minimize button and pick "FETCH THE RESTORE BUTTON". The next time that you minimize, the Restore Button will be right there. This time be more careful where you leave your playthings.

Color Erase Button
The Color Erase button appears after an action that caused a candidate to become colored (e.g. a hint or Alt-click). Clicking the Color Erase button will restore all of the candidates to their original beautiful dark gray color.

The Context Menu
To access the context menu, right-click anywhere on the widget.

About Sudoku Solver Widget
Click this to reveal embarassing facts about the author of Sudoku Solver.

Widget Preferences ...
Click this to open the Widget Preferences window. Preferences unique to Sudoku Solver are described later.

Open recent puzzle ...
Click this to reload a recent puzzle. Up to 25 puzzles are shown, with the most recent on top. Only puzzles generated with New, loaded from file, or entered through Paste or Keyboard are shown, (puzzles entered manually by entering each number into individual tiles are not).
Checking the "Clear Recent Puzzle List" and selecting "Ok" will erase all but the first (most recent) puzzle without loading any puzzle.

Open from file ...
Click this to open a File Open dialog. A previously saved puzzle, or a puzzle imported from other sources (see description on File Formats), can be opened.

Save to file ...
Click this to open a Save File dialog. The current status of the puzzle (along with undo history) is saved to a file of your choosing, for later retrieval.

Save to file (short format) ...
Click to open a Save File dialog. The current status of the puzzle (without undo history) is saved to a file of your choosing, using a short format. (See description on File Formats).

Copy
Click to save a puzzle to the system clipboard in the short format.(Note: Only 9x9 puzzles can be saved in short format).

Paste
Click to input a puzzle from the system clipboard.

Input from keyboard ...
Click to open an input dialog. Puzzles can be entered from the keyboard (in the short format) or copied from the system clipboard.

9x9 Board Size
Click to change the board dimensions to 9 by 9 tiles. Changing board size will reset the board.

12x12 Board Size
Click to change the board dimensions to 12 by 12 tiles. Changing board size will reset the board.

16x16 Board Size
Click to change the board dimensions to 16 by 16 tiles. Changing board size will reset the board. (Note: Little Jimmy is all better now!).

Check for Update
Click to see if your version of Sudoku Solver is the latest available.

Help
Click to see this help page. If you are not seeing this help page, it is possibley due to you not having a default web browser on your system. You should fix that.

Close Widget
Click this when you have had quite enough of the Sudoku Solver. But you'll be back. Oh, yes, you will be back.

Widget Preferences
There are many preferences that can be set to change the look and behavior of the Sudoku Solver. The Window group does not contain any non-standard preferences. Preference changes should take effect immediately.

General Group
The General group contains preferences that change the way the Sudoku Solver behaves.

Hint Text
Options for hint text are Long, Short, and None. As you get more experienced in using the Sudoku Solver, the less hint text you will want to see.

Tool Tips Off
Check this box when you are sick and tired of tool tips.

Super Hint On
With super hint on, putting your mouse on a candidate will make the same numbered candidates in the same row, column and square appear pink.

Don't Ask Stupid Questions
Check this option when you get sick of pop-ups telling you things that you already know. If you have responded to an annoying pop-up with firm resolve, this option will be automatically selected.

Screen Size
Select Auto if you want the size of the display to depend on the resolution of your monitor.
If the auto size is not to your liking, you can select Fixed Small, or Fixed Large.

Look Group
The Look group contains preferences that change the way the Sudoku Solver appears.

Tile Texture
Select between Plain, Generic, Wood or Marble texture for the board.

Color Scheme
Opens the standard color selector window. Pick the color that best reflects your individual tastes. Some colors to not work well with the shading. In order for the color selection to be effective, you must also select Apply Color.

Apply Color
Check this box to apply the color you have selected in Color Scheme.

Font Scheme
Opens the standard font selector window. Pick the font that best appeals to your eye. Note: Despite my best effort to make up for deficiencies in the Yahoo! Widget Engine, some fonts will not render properly even though they are available to choose. Sorry.

Bold Font
Will make the numbers bold (if the selected font supports it).

Italic Font
Will make the numbers italicized (if the selected font supports it).

Border
Select between Border or No Border. I prefer to go borderless, myself.

Advanced Group

The Advanced preferences are for users of above average intelligence and should not be entered into lightly. Changes made here can cause careers to crumble and civilizations to fall. caveat populi

Pltboi Option (No Help)
This option is for users, (like "pltboi"), who want to "do it themselves". With pltboi option on, the automatic candidate functions and hint functions are disabled. Clicking on a tile will bring up a small window where you can select to enter a solution number (the big black numbers on the left) or a candidate (the smaller gray numbers on the right). The "X" in the corner is to close the small window if you decide not to enter a number.
Candidates entered manually still respond normally to click, alt-click, and shift-click. However, do not expect the selection of a candidate to erase candidates in other tiles. That would be helping.
Clicking a selected (large) number will erase it and leave the tile blank, but using the Undo button will restore the candidates that were present before the number was selected. Shoot, it even restores the candidate of the selected number whether you put it there or not!

Character Set
When you get tired of seeing the same old numbers 1 through 9 in your puzzle, you can make changes here. Note: You must enter exactly 16 characters here, or else it won't take effect.(And, unless you're some kind of masochist, they should be 16 different characters). The first 9 characters are used for 9x9 puzzles, the first 12 are for 12x12, and ... well, you get the point. Put in letters and, voila, you've made a Godoku puzzle!
With careful selection of font and characters, you can even have a puzzle with special characters and buttons that still make sense.

Use Character Set
To enable the character set set in Character Set, check this box. Otherwise the standard 1-G characters will be in effect.

File Formats
Sudoku Solver not only supports its own proprietory file format, but also many (well one in a great number of variations) of the popular formats.

Puzzles saved in the short format will lose all undo information and any erasures of candidates. The only information captured in the short format is the selected numbers.

The format is essentially this: non-numbers (including 0) where tiles are blank, and a number where the tile has a number selected. 81 characters total are required, and (in files) line breaks are ignored.

These are all valid short formats for the same puzzle:
       4.6.5.12....4....8.92....7..2..8....7..1.3..6....9..4..1....56.2....5....45.1.3.2
       4*6*5*12****4****8*92****7**2**8****7**1*3**6****9**4**1****56*2****5****45*1*3*2
       406050120000400008092000070020080000700103006000090040010000560200005000045010302
       4 6 5 12 4 8 92 7 2 8 7 1 3 6 9 4 1 56 2 5 45 1 3 2

And for files, even this:

       4.6.5.12.
       ...4....8
       .92....7.
       .2..8....
       7..1.3..6
       ....9..4.
       .1....56.
       2....5...
       .45.1.3.2

Some special characters are ignored, so files like this can be used:

       5.2|6..|7.. 
       ...|9..|.1. 
       ...|...|385 
       ----------- 
       ..4|.96|1.. 
       ...|...|... 
       ..5|27.|9.. 
       ----------- 
       837|...|... 
       .6.|..9|... 
       ..9|..8|2.3

Valid files can be dragged and dropped onto the board.

Hint Logic
When you hit the Hint button, Sudoku Solver will test the puzzle using several different types of solving techniques. First it looks to see if there are any mistakes that will make the puzzle unsolvable. This is not a exhaustive test, and only looks for obvious things like an absence of a specific candidate in a row, column or square, or the absence of any candidates in a tile.

Next, eight different solving techniques, (Naked Single, Hidden Single, Block to Row/Col Interaction, Block to Block Interaction, Naked Subset, Hidden Subset, XWing, and Swordfish), are employed in order of (roughly) increasing complexity until one produces a usable hint. None of the techniques use a computer's ability to quickly run through several trials and errors. All of the techniques are logically sound.

Some techniques allow you to select a candidate as the only possible entry for a tile. The candidate will be colored RED and can be selected with confidence.

Other techniques allow you to eliminate one or more candidates on the board. Candidates that are to be erased will be colored YELLOW and the candidates that caused the yellow candidates to be logically eliminated will be BLUE. There is nothing you need to do with the blue candidates other than learn from them. To return the blue candidates to their original color, press the Color Erase button.

The hint logic is not exhaustive. There are logical techniques that have not been implimented, and probably never will be. I'm sorry. Mia culpa. If no techniques result in a hint, you will be treated to the none too encouraging message that you are on your own.

Undocumented Easter Eggs
Undocumented Easter eggs are not "features". They were created to help speed up troubleshooting time. That is why they are undocumented.

Hint Button

If you hold down the "Alt" key when you click the Hint button, the puzzle will be solved for you automatically. The level of solving techniques that will be used is set by left-clicking on the Hint button and selecting one of the "Solve" items. So, if you have selected "Solve Through Hidden Single" and alt-click the Hint button, the puzzle will be solved up to the point where the "Block to Row/Col" (or higher) technique is needed.

Another non-feature of the Hint button is found if you hold the "Shift" key while clicking. In this case, the order of the solving techniques are applied in reverse order. Unlike other undocumented non-features, this one has absolutely no troubleshooting value at all. On the other hand, it may be the only time you ever see the "Swordfish" technique found.

Color Erase Context Menu

There is an extra context menu item available when you left-click over the Color Erase button. It allows you to save some of the internal data to file. It is totally useless for you, so you should not waste your time trying it out. In fact, you should not even waste your time reading this.

Sudoku Websites
There are more Sudoku websites on the net than there are books (see How to Play Sudoku). Here are two that I use quite a bit.

SadMan Software: Techniques for Solving Sudoku
(http://www.sadmansoftware.com/sudoku/techniques.htm)
Simon Armstrong has put together an amazing site that explains, illustrates, and provides examples of Sudoku solving techniques. There's a lot to be learned here. The example files can be downloaded and input into the Sudoku Solver,(so you can see exactly where the hint system breaks down).

Sudoku Generator, version 2.5
(http://www.geocities.com/jaapsch/sudoku.htm)
Jaap Sherphuis has made an excellent Sudoku puzzle generator. The versitality of this program must be seen to be believed. The puzzles generated can be copied and pasted into the Sudoku Solver.