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Sudoku Strategies - Analysis
When
carrying out the Sudoku Strategy of Analysis on a Sudoku grid there are
two key methods that you can use. These are: "candidate elimination"
and "back tracking". In candidate elimination the aim is to eliminate
candidate numbers from squares to leave one choice. Once this has been
done another scan is carried out - normally to check the effect
the newly discovered number or numbers have had on the contingencies.
Candidate elimination generally works like this; if you enter a
particular number into a row and it doesnt allow you to complete the
column or region it is eliminated as a candidate.
When using the "back tracking" approach you single out a cell that has
two potential candidate numbers, and bascally guess which one of the
two candidate numbers should be in that cell. If a duplication is found
in a row, column or region or a cell is left without a possible
candidate number, than the alternative is the solution
These two methods of analysis can be best summed up with a question
that you should ask yourself when attempting to resolve a Sudoku puzzle.
"will entering a certain number prevent the completion of other
placements of that same number (in a row, column or region? If yes the
candidate should be discarded. This question should be asked for
each cells candidate"
In regards to the "back tracking approach if both numbers are possible
candidates another pair should be tried.
If you decide to use the "back tracking"method you will need to have a
pencil and an eraser handy .
More Sudoku Strategies are discussed in other articles on this website.
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