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Sudoku Strategies - Scanning
When
attempting to complete a Sudoku puzzle there are 3 main strategies that
you should employ to help you solve it. These strategies are scanning,
marking up, and analyzing. In the is article we'll be looking at the
Sudoku Strategy - Scanning.
Scanning should be the first strategy you employ when trying to solve a
Sudoku puzzle, it should also be used strategically throughout the the
whole puzzle solving process.
There are two different techniques involved in scanning, these are
Cross- Hatching and Identifying Missing Numerals by counting 1-9 in the
rows, columns and 3x3 squares.
Cross-Hatching
This Sudoku strategy involves scanning the rows of a Sudoku
puzzle to
work out which line may contain a number by process of elimination.
This same process is then carried out on each column. The rows with the
most numbers should be scanned first as this makes the whole
process faster. All the digits should intially be checked using this
method, missing out some will just make the puzzle more difficult.
Identifying Missing
Numerals by counting 1-9 in the rows columns and 3x3
squares.
When a you discover a missing number by cross hatching, it is a good
idea to count the row, column or 3x3 square as this can help you find
other missing numbers in the puzzle. It is also wise to scan in reverse
in order, that way you will be able to see which values are not the
missing numerals, hence narrowing down the possibilities.
When attempting to solve Sudoku you also want to be looking for
"contingencies" while scanning, this is done by narrowing down the
location of a numeral within a column or row to 2 or 3 squares. When
the squares lie within the same row and region or, column and region
cross hatching and counting can be used for elimination. Puzzles that
can be solved with scanning, but without having to look for
contingencies are classified as easy, because scannning is a basic
method for solving Sudoku puzzles. More Sudoku Strateges are
discussed in other articles on this site,
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