kjodle/sudoku-zine
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Updated with sections and named subgrids

Browse Source
This commit is contained in:
Kenneth John Odle 2025-04-23 11:12:03 -04:00
parent e8b2b1fa00
commit bf502d07d9
1 changed files with 39 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
sudoku.tex
View File

@ -248,6 +248,8 @@ If you want to donate financial support for the creation of this zine (and all t
Sudoku puzzles have anywhere from a few to many of the cells filled in with numbers. Those puzzles with more cells filled in are generally easier to complete than those with only a few cells filled in.
\section{A Brief History}
Number puzzles of this type have been around for a long time, with one of the earliest appearing in 1892 in the French newspaper \textit{Le Siècle}, which was a partially completed 9x9 magic square\footnote{A square array of numbers in which the sum of numbers in each row, column, and both diagonals add up to the same number.}
Despite the Japanese name (which translates roughly as ``digit-single'' or ``number-unique''), the modern sudoku puzzle is apparently an American invention, first appearing the May 1979 issue of \textit{Dell Pencil Puzzles \& Word Games} as ``Number Place''. It is apparently the work of a retired architect named Howard Garns, although the evidence is somewhat circumstantial: Garns appeared in the list of contributors in each issue that did contain a ``Number Place'' puzzle, but did not appear in the list of contributors in issues that did \textit{not} contain a ``Number Place'' puzzle.\footnote{See \kref{https://www.mathpuzzle.com/MAA/41-Sudoku Variations/mathgames_09_05_05.html}{https://www.mathpuzzle.com/MAA/41-Sudoku\%20Variations/mathgames\_09\\\_05\_05.html} for more information, which also contains more information on sudoku variations.}
@ -263,7 +265,9 @@ Despite the Japanese name (which translates roughly as ``digit-single'' or ``num
It was later imitated in the 1980's by the Japanese publisher Nikoli who introduced two small improvements: the number of clues was limited to 32, and the clues were distributed in a rotationally symmetric way, meaning that the clues were more evenly distributed across the grid.
In 1997, Wayne Gould, a retired judge from New Zealand who had moved to Hong Kong spotted the puzzles in a Japanese bookshop and then spent the next six years developing a computer program to create sudoku puzzles, and started selling them local newspapers and eventually to the London \textit{Times}. He also publishes them from his own website at \kref{https://sudoku.com/}{https://sudoku.com/}.\footnote{See \kref{https://www.theguardian.com/media/2005/may/15/pressandpublishing.usnews}{https://www.theguardian.com/media/2005/may/15/pressandpublishing.u\\snews} for more information.}
In 1997, Wayne Gould, a retired judge from New Zealand who had moved to Hong Kong spotted the puzzles in a Japanese bookshop and then spent the next six years developing a computer program to create sudoku puzzles, and started selling them to local newspapers and then eventually to the London \textit{Times}. He continues to publish them from his own website at \kref{https://sudoku.com/}{https://sudoku.com/}.\footnote{See \kref{https://www.theguardian.com/media/2005/may/15/pressandpublishing.usnews}{https://www.theguardian.com/media/2005/may/15/pressandpublishing.u\\snews} for more information.}
\section{Possibilities}
There are 6,670,903,752,021,072,936,960 possible sudoku puzzles possible, but many of them are reflections or rotations of one another. When those are accounted for, there are 5,472,730,538 truly unique sudoku grids, which is a considerably smaller number, but means that you are unlikely to run out of sudoku puzzles to play.\footnote{See \kref{https://web.archive.org/web/20171112153047/http://www.afjarvis.staff.shef.ac.uk/sudoku/}{https://web.archive.org/web/20171112153047/http://www.afjarvis.sta\\ff.shef.ac.uk/sudoku/} for more information on how these numbers were calculated and information on other variants (such as 2x3 and 2x4 grids).}
@ -286,6 +290,40 @@ Winning is simple: you win when you have filled in the entire 9x9 grid according
There are a number of different strategies that you can employ to solve a sudoku puzzle.
For clarity, we will refer to individual cells in the form ``C4R5'' and we will refer to the subgrids like this:
\begin{wrapfigure}{O}{0.45\textwidth}
\centering
\begin{tikzpicture}[x=5mm,y=5mm]
% Thick horizontal lines
\draw [ultra thick](0,0)--(9,0);
\draw [ultra thick](0,3)--(9,3);
\draw [ultra thick](0,6)--(9,6);
\draw [ultra thick](0,9)--(9,9);
% Thick vertical lines
\draw [ultra thick](0,0)--(0,9);
\draw [ultra thick](3,0)--(3,9);
\draw [ultra thick](6,0)--(6,9);
\draw [ultra thick](9,0)--(9,9);
% Subgrid names
\begin{Large}
\node at (1.5,1.5) {SW};
\node at (4.5,1.5) {S};
\node at (7.5,1.5) {SE};
\node at (1.5,4.5) {W};
\node at (4.5,4.5) {Cent};
\node at (7.5,4.5) {E};
\node at (1.5,7.5) {NW};
\node at (4.5,7.5) {N};
\node at (7.5,7.5) {NE};
\end{Large}
\end{tikzpicture}
\caption[]{Named subgrids.}
\label{subgrids}
\end{wrapfigure}
\lipsum[1]
\section{Last Free Cell}
This strategy is based on the rules that each 3x3 subgrid, row, and column, cannot contain duplicate numbers. Thus, if only one cell remains empty, you can use the process of elimination to figure out which one it is.