数独 - A Su Doku solver
The Times newspaper displays a Su Doku problem
in its T2 supplement each day. (Alternatively, visit
the website and click on the GAMES button underneath the top
advertising banner). Although the problem will be far from straightforward for
most readers to solve, an average home computer will be able find the solution
in less than a second.
Readers of The Times who are motivated less by intellectual challenges
and more by daily offers of champagne should visit the
Sudoku solutions site. Select 'The Times (of London)' from the choice
box in the bottom-right hand corner, enter the first five grid values from the
paper and press 'Find Solution'. The site will very kindly pop up the answer to
the current puzzle, ready to be e-mailed to the The Times. Thanks to Nigel
'Loadsabubbly' Greenwood for that tip!
The goal of a Su Doku problem is to complete the published grid so that no
number appears more than once in any row, column or 3x3 subgrid. The rules are
described more fully on the official Su Doku website, to which a link is
provided above. To set up the solver, simply type the numbers printed in The
Times into the corresponding squares in the grid below. (The Tab and Shift-Tab
keys allow the grid to be navigated without use of the mouse). Squares that are
blank in The Times should be left blank in the grid. Once all the values have
been copied across from the newspaper, use the buttons beneath the grid.
Instructions appear underneath.
There are three solve buttons:
Solve completes the grid (provided that a solution exists).
Unsolve resets any squares on the grid filled by a previous press of the Solve
Reset resets the entire grid.
Evaluate checks to see whether the current incomplete grid has a unique
The drop-down list to the right of the Evaluate button allows the user
to switch between the 'Numeric from 1' format used by the majority of
sources and the 'Alphanumeric from 0' format used by the 4x4 puzzles in
Copy transfers the current grid into a separate clipboard window (the
system clipboard cannot be used for security reasons) in the format selected in
the drop-down box on the far right of the row. The two supported formats are Plain
Text and Library Book (the XML format used by the Pappocom
Sudoku software). Once Copy has been pressed, simply select the
displayed grid in the clipboard window, press Ctrl-Insert to copy it, then
press Shift-Insert from within some other document, such as a new e-mail
message. The grid will look its best rendered in a monospaced font such as
Courier. Paste performs the opposite operation, i.e. it transfers a grid
from the clipboard window (which must have been previously opened by a press of
the Copy button) to the solver. (Only the Plain Text format is supported
by the Paste operation). Suppose you have received an e-mail that contains a Su
Doku puzzle in the approved clipboard format. Select the grid from within the
document, then press Ctrl-Insert in order to copy the grid to the system
clipboard. Press Shift-Insert within the clipboard window to copy the text
there, then press the Paste button to copy the grid from the clipboard
window into the solver.
Although classical Su Doku puzzles use a 3x3 grid of boxes, the Su Doku Solver
supports the alternative box grids that are sometimes seen. Use the Resize
button to change the grid size. Be aware that the grid might not display
properly if a very large grid has been chosen.
Compose composes a fresh puzzle. The new puzzle is certain to be
symmetrical, have a unique solution and feature the requested number of filled
cells. Note that complicated puzzles (in the case of the classic 3x3 Su Doku
puzzle, 'complicated' usually means with less than 24 filled cells) might take
a considerable time to generate. Press Break in order to interrupt the
The Patterns section dictates which patterns should be detected during the
Solve phase. The meanings of the various patterns are discussed on the
Sudoku Programmers forum. The numbers to the right refer (except in the
case of Guess) to the total number of candidate move eliminations performed due
to the discovery of each type of pattern. In the case of Guess, the figure is
the total number of guesses performed.
The text box at the bottom displays the reasoning that has been used to solve
the puzzle. Click part-way through the reasoning in order to view partial