# Sudoku puzzles how to solve | How to do sudoku

How to do sudoku ? Let’s be clear. Sudoku explained in brief. Sudoku is a logic game with a schematic matrix. Except for card games and particular versions of Sudoku (e.g. the Circular Sudoku, which is little known, or the so-called “Samurai Sudoku”), the logic games of the Sudoku category have more or less all the same structure. The basic grid (matrix) consists of 9×9 cells. In the matrix there are already 2 to 5 digits, distributed more or less uniformly. The greater number of digits already indicated, the easier it will be to solve the game. The aim of the game is to fill all the empty boxes with the numbers from 1 to 9, so that in each column (vertical), in each row (vertical) and in each region (3×3 cells) are present all the digits from 1 to 9, without repetitions.

Sudoku Rules

The rules of Sudoku are easy. Each game consists of 3×3 blocks (or regions), which are divided into 3×3 boxes. The result is a total of 81 squares, divided into 9 rows and 9 columns. In some boxes the numbers are already indicated. The higher the difficulty level, the less digits will be shown at the beginning of the game to help you solve it. Empty boxes must be filled in with all digits 1 through 9. Each digit can only be entered once within each region and in each row and column of the entire matrix. It seems easier than it really is. Below you will find strategies for solving Sudoku. How to do sudoku: two simple methods of resolution. To solve Sudoku you don’t have to follow a particular strategy. There’s no question, however, that a well-structured GAME STRATEGY can make it easier to solve.

Strategy 1:

Analyse the values of the columns and limit the possible alternatives to a minimum. This resolving strategy, particularly ideal for filling in the first boxes, consists in searching for the parts of the grid in which, on the lines, numerous figures are already contained. By gradually excluding the digits from 1 to 9, at best you are able to go back to the only digit allowed in a box. In any case, you can limit the number of digits allowed in each box to a minimum. On the basis of this principle, you can fill in, step by step, all empty Sudoku boxes that meet these criteria.

Strategy 2:

The only possible number. This strategy of solving Sudoku requires that you first take into account the individual blocks of the grid. Often you find columns, directly parallel to each other, with the same values. If you find columns of this type in your Sudoku, we recommend that you proceed as follows: look for the third parallel column and evaluate in which box of the block to enter the required number. Most of the time there is only a maximum of two acceptable boxes, and if you’re lucky, you’ll immediately find the right box. With this scheme, you will be able to check all the parallel lines of Sudoku. It is often worthwhile to combine, in a flexible way, the different strategies for a faster resolution of the game and to limit the risk of entering wrong numbers.

The method of attempts and errors in lock situations

Things don’t always go smoothly. We have completed the list of candidates in each cell, but we cannot find a situation where we can make final decisions. All that remains is to proceed by trial and error. For example, we could consider a pair of cells to be assigned to a one-two, or a lone figure that is only twice nominated in a row or column or box. We have no elements to decide which of the two cells to assign to the pair or to the solitaire. So we decide to make an attempt, assigning automatically the two cells to each element of the pair or one of the two cells to the solitaire. We will keep in mind the situation of the row, column and box next to the two cells examined, as well as a chess player who examines all possible counter moves before moving a piece. We will choose the path that will seem more productive for the purposes of the continuation of the game.

It is not said that the most promising way is the best one, but it is always better so, rather than rely only on chance. Once you’ve made your decision, you go back to the game. In most cases, you’re able to break the deadlock and the game regains momentum. The elimination of candidates, now settled, albeit provisionally, reduces the list of candidates in the other cells and it turns out that in some of them remains again only one candidate. If the choice made was the right one, the whole scheme can be completed. If, on the other hand, we have made the wrong choice, the very nature of sudoku (which we remember means single number) will eventually lead to a contradictory situation: for example, in a certain cell should be forced to put a certain number, but during our attempt, it has already found a place in another cell of the row, column or box and it is therefore not possible to insert it a second time.

We can always pick up where we were before we make our attempt. Having chosen to work on only two possible cells makes the task easier for us: if we had previously arranged the figures in a certain order in the two cells, it will be enough to reverse the order. This time we are sure not to be wrong: if there are only two ways to fix two boxes, surely one of them is the right one. It’s not certain that this time we’ll get to the sudoku solution without any further hiccups. Is quite complex situations, in which it was necessary to use more than once the method of attempts and errors, before finally unlocking a stalemate. Sudoku is a game of skill, intuition, but also patience. Choosing to use the spreadsheet made the task easier : before making every attempt, save on the computer the situation at that time. If the attempt went wrong, just close the file without further saving and then reload the file as it had been saved before the attempt. Those who prefer to use a  pencil and eraser will have a little more difficult. Resources: Sudoku Video Tutorials