Sudoku is one of the most popular and fun puzzle games available across the globe. It is fun to play and quite addictive. However, since it is a brain-teasing game and requires utmost concentration, it is very easy for a player to get stuck. So don’t think that it is uncommon to get stuck while playing Sudoku. In fact, many players, especially beginners are more likely to get stuck while playing Sudoku. Fortunately, there are plenty of strategies that can help you unstuck if you get stuck when playing this popular puzzle game.
In this article, we are going to explore some of the strategies that players can use when they are stuck while playing a Sudoku puzzle game. So without wasting too much time, let’s delve into them.
Following Sudoku’s One Rule in which column, row, and block consists of 1 to 9 digits without repetition, the single candidate or hidden single applies. This means that if a certain digit can be placed in that particular column, row, or block, then it is a perfect fit.
2. Sole candidate
This technique is used when particular cells consist of a single number. When all the other digits, except the possible candidate, fall under the current column, row, or block, it is a sole candidate. It is like when all possibilities are gotten rid of after scanning, only one choice remains, which is the corrected value.
3. Naked Subset
This concerns the cells that have only a specific number of candidates. The player can quickly and efficiently spot naked subsets when all the remaining candidates have been placed. This means that if two cells containing the same two contain the same two candidates in a column, row, or block, they can be excluded from the cells of another column, row, or block.
4. Forcing Chains
This is probably one of the most difficult strategies of all these. It tells you precisely what number a given cell would hold. It allows the player to take a look at cells that exactly have two digits as candidates. Whichever digit is chosen for one, the other cell will be forced to be of another value.
5. Hidden Subset
When using this strategy, instead of affecting cells of other columns, rows, or blocks, hidden subsets affect the pair, triplet, or quad of the same subset. If you are using the assistance of the computer to get a complete candidate listing for all cells, these are the ones with specific numbers that are hidden among other candidates for those particular cells.
6. The X-Wing Technique
This method essentially uses the fact that in specific cases, there are only two possible ways to place two numbers in four squares to form a rectangle. Basically, there is a connection between the diagonally opposite squares, thus the “x” in x-wing. The word x-wing is derived from the x-wing fighters in Star Wars.
So let’s say you come across a Sudoku that has been partially solved using either easy or medium difficulty solving strategies. This means no more blocks can be solved with these techniques so you are stuck!
You need to find a place to place the number. You know it should be placed once, and only once, on each of the rows. Generally, an x-wing is found when for two rows, there are two possible squares where a particular number can be placed, and for both rows these squares lie in the same two columns. In this case, this particular number can be done away with as a possibility for all other squares in those two columns. Of course, it is possible to exchange columns and rows in this definition.
7. The Swordfish technique
This technique is a complex version of X-wing. But is generally a technique for advanced puzzles. The Swordfish technique is almost similar to the x-wing technique, but with three rows and columns instead of two.
The Swordfish is named after a World War II biplane by the name “Fairy Swordfish,” a Torpedo Spotter Reconnaissance biplane which was used by the Royal Navy between 1936 to 1945. If you draw lines alongside the columns and the row and they connect the squares given, they will form two rectangles. This looks like the wings of a biplane, separated by struts.
A swordfish is basically found when for three rows, there are two possible squares where a particular number can be placed, and for all three rows, these squares lie in the same three columns. If this is the case, this specific number can be removed as a possibility for all the squares in those three columns. Of course, the rows and columns in this definition can be exchanged.
Remember that there are no easy routes to spotting the Swordfish pattern. However, you should try focusing on just one number 1-9 in turn as you can mark in columns and rows. You need to take a look at each row in turn, noting each one that contains only two or three squares with the current number as a possibility. Then look if there are three rows where the squares fall into 3 columns. If you find nothing, you can try again with the columns in place of the rows.
As mentioned above, Sudoku is a puzzle game that can be quite complex and it easy to get stuck, especially if you are a beginner. But if you get stuck, it doesn’t mean that is the end of the game and there is nothing you can do. Fortunately, there are plenty of strategies you can use to unstuck. These ones named above are some of the basic and advanced level Sudoku solving strategies. So if you are playing a Sudoku and you are stuck, you can choose any of the above techniques or you can try all of them and solve your Sudoku puzzle.
We hope that you find this article helpful!