If you’re one those players who hate guessing at Sudoku, try these Sudoku solving techniques instead. We know how it feels after making most moves by pure luck and not logic. You may succeed once, but it isn’t always the case. So, make use of these simple yet surefire strategies if you ever get stuck:
This happens when particular cells contain a single number. When all other digits, except the possible candidate, fall under the current row, column, or box, it’s a sole candidate (naked single). It’s like when all possibilities are eliminated after scanning, only one choice remains, and that’ll be the correct value.
Following Sudoku’s one rule where each box, row, and column must contain digits 1 to 9 without repetition, the single candidate/ hidden single applies. So if a particular digit can be placed in a said row, column, or box, it’s a perfect fit.
This technique concerns the cells containing only a specific number of candidates. You can quickly and efficiently spot naked subsets (pair/ triplet/ quad) when all the remaining candidates have been placed. So if two cells have the same two candidates in a row, column or box, they can be excluded from the cells of another row, column, or box.
Instead of affecting cells of other rows, columns, and boxes, hidden subset impacts the pair/ triplet/ quad of the same subset. If you use computer assistance to get a complete candidate listing for all cells, these are the ones with specific numbers hidden amongst other candidates for those cells.
This technique works with cells forming a rectangle, and it also occurs in rare situations. X-Wing is a pattern spanning multiple columns and rows claiming the candidates to be eliminated from other relevant rows and columns.
Swordfish is a complex version of X-Wing. But it’s a master technique for advanced puzzles. Where the columns may contain more than three candidates, rows may not. This way, you can eliminate candidates on the column except for the ones making a swordfish. It also works vice-versa.
This one’s not too easy to use, but it precisely tells you what number a particular cell would hold. It allows you to look at cells that exactly contain two numbers as candidates. Whichever value is chosen for one, the other cell is forced to be of another value.
So that’s it!
There are more challenging and complicated strategies, including XYZ-Wing, 3D Medusa, and X-Cycles, but that’s a whole different discussion topic.
The ones above are basic to advanced level Sudoku solving techniques, especially for cracking a puzzle you’re stuck at.
We hope you find these are useful!