This game of Su-doku is played on a 9x9 board of 81 cells.
The board is divided into 27 UNITS:
Thus each UNIT (Row, Column or Square) contains nine cells
The object is to place on the board the digits 1 to 9, so that each digit occurs only once in each UNIT, and every one of the 81 cells contains a digit.
A sample completed game is shown below.
1 2 3 4 5 6 7 8 9
4 5 6 7 8 9 1 2 3
7 8 9 1 2 3 4 5 6
2 3 4 5 6 7 8 9 1
5 6 7 8 9 1 2 3 4
8 9 1 2 3 4 5 6 7
3 4 5 6 7 8 9 1 2
6 7 8 9 1 2 3 4 5
9 1 2 3 4 5 6 7 8
Each time Extreme Su-Doku is started, it will automatically restore the last game you were playing.
You may choose at any time to ask Extreme Su-Doku (via its FILE menu) to:
The origin of modern Su-Doku was the Latin Squares, a game which Euler invented in the 1780s. The 9x9 Su-Doku game is itself a 9x9 Latin Square which in turn is built up of nine smaller 3x3 Latin Squares.
Why "Extreme" Su-Doku?
To make a game easier to solve, it may contain redundant information. Extreme Su-Doku's games contain NO redundant information of this sort.
Extreme Su-Doku is designed to be played without a keyboard on either:
These instructions assume you are running on a PocketPC.
The playing area consists of the 9x9 board already discribed, and a Menu bar which has:
A cell on the board is selected by taping it with the
stylus. It's colour will change.
A digit on the menu bar is selected by taping it with the stylus.
Placing a digit in a cell is a two stage process:
A cell colour may be:
An incorrectly placed digit in a cell may be replaced by either the correct digit or a blank (select Cell Reset _ on the menu bar).
The Cell Reset menu item performes several tasks:
If you get stuck, help is available via the Aids menu.
The File menu, offers several options such as the ability to restart, save and restore games.
The options available on the file menu are:
If you get stuck, help is available via the "Aids" menu:
"Valid" does NOT imply "correct", merely that the rule
against duplicate digits in a UNIT has NOT been broken.
The "Highlight" option is active by default.
The "Highlight", "Cells" and "Numbers" options are mutually exclusive.
The "Numbers" option also highlights any cells with only one valid number.
You may also highlight individual cells, with a stylus tap-and-hold or Left Mouse button click.
This program initially assigns to each game a Difficulty Level.
The levels shown in the title bar are normally selected from:
Trivial, Very Simple, Simple, Easy, Moderate, Hard, Very Hard, and Fiendish.
Games up to a Moderate level can all be solved with logic, harder games may require an element of "trial and error".
Assigning a Difficulty Level to a game is a very subjective exercise. Extreme Su-Doku does it by looking at several factors, giving each a value, with the total score achieved defining the difficulty level. Some factors relate to the game's initial position; others to how Extreme Su-Doku goes about solving empty cells.
The factors relating to the initial position are:
The factors relating how Extreme Su-Doku solves empty cells:
Games can also be classed as:
Difficulty Level - Notes:
A clear board is classified as Undefined.
The Recalc option will re-calculate the Difficulty Level from the current position.
A valid game with more than one missing digit, must have Multiple solutions.
Extreme Su-Doku should never create an initial game with Multiple solutions.
Ray Cannon's Extreme Su-Doku - for Desktops and PocketPCs
Author - Ray Cannon
Copyright © 2008 Ray Cannon
Dyalog APL Version 11.0.2