Sudoku Solving Strategies

No matter what level of puzzle you are attempting to solve there are two basic strategies that will allow you to find and place correct numbers in empty cells. These sudoku solving strategies are demonstrated in sudoku video tutorials advertised to the right.

Counting

Counting is the process of counting from 1 to 9 in row, columns, and regions so that you can tell if there are any missing numbers. The main rule of sudoku: “if a number is right for a cell, this is true for the region and the intersecting row and coloumn is important here. You don’t count the region, row and coloumn separately. You should start with one cell and then check the presence of numbers 1 through nine for the region and the intersecting row and coloumn.

If you are working harder puzzles the value of one single cell can often be determined by counting in reverse. This is done by scanning the region, the row, and the column for numbers that can’t be right to see which numbers are left that might work.

Cross-hatching

Cross-hatching starts by scanning the rows and columns to see if the presence of a number in the row or coloumn blocks any cells in the region. The main rule of sudoku – if a number is right for one cell, this is true for the region, row and coloumn – also applies here. A number given in a cell in a row or a coloumn, will not occur in any region intersected by this row or coloumn.

You repeat the process for every row and column. To make things even faster, scan the numbers in their order of frequency. Perform cross-hatching systematically by checking for all the digits from 1 to 9 in order.

Guessing

Try not to guess. Until you have progressed to the tough and diabolical puzzles, guessing is not only totally unnecessary, but will lead you up paths that can make the puzzle virtually unsolvable. Simple logic and a structured approach is all that is required for gentle and moderate puzzles. Most puzzles that are rated easy to hard will be solved by the basic strategies and a minimum of analysis.

Contingencies

Once you become advanced in solving Sukoku Puzzles you will learn to look for what are called contingencies while you are scanning. This means that you will narrow down the location of a number within a row, column, or region to two or three cells. When each of those cells fall into the same row, or column, of the region, then you can use them to eliminate other numbers by cross-hatching and counting.

Sudoku puzzles that are really challenging might require you to try multiple contingencies. There will be times when you have to recognize these contingencies in multiple directions while at times even intersecting your number selection.

A sudoku puzzle will be classified as “easy” if you can solve it by the counting and cross-hatching alone. More challenging sudoku puzzles will need more advanced sudoku solving strategies.