How to use x wing in sudoku

X-Wings are fairly easy to spot, but a little harder to understand than some other techniques. Like others it relies on using positions of pencilmarks to infer enough to allow you to eliminate some other candidates.

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How to use x wing in sudoku

The Sudoku X-Wing pattern or technique is one of the most advanced techniques that can be applied to Sudoku puzzles from a medium difficulty level onwards. It is a very forthright method with a simply discernable pattern. It emphasizes one single digit, and its goal is to confine the number of cells that can have that number as a possible candidate. Sudoku X-Wing technique is also a valuable strategy for any player to learn as it branches out into more complex patterns and techniques that are required to solve impossible puzzles. In this article, I use one of my handcrafted, very difficult puzzles that have a known X-Wing pattern. Go ahead, download and print out this PDF very hard Sudoku puzzle 1. You will need to partially solve the puzzle to reach the picture shown. You will need to solve naked singles, hidden singles, a naked pair 4,7 in row 7, a locked candidate 5 in column 7, and a naked triple 2,4,5 in column 1 first. If these terms are not familiar, read my article Sudoku Tips for an illustrative guide. An X-Wing pattern occurs when two rows or two columns each contain only two cells that hold a matching candidate. This candidate must reside in both rows and share the same two columns or vice versa.

X Wing An X Wing is a technique for removing candidates pencil marks.

If you can find a row that contains the same pencil mark in exactly two spots, as well as another parallel row that mirrors it — containing the same pencil mark in only the same two spots, then you can use this information to eliminate similar pencil marks in the columns passing through those spots. Because of this, we can safely assume that either the light blue cells or the dark blue cells must be 4s. Armed with this, let's zoom out all the way and shift our focus to the columns involved here indicated with arrows below. Based on what we said above, the 4s in these columns must exist where these two rows cross - that is, where the blue 4s are. Knowing that, all other 4s in the columns are not possible, and can be erased erase all the pink 4s.

Love puzzles? Play Jigsaw Puzzles! New Game. Home How to Play. How to Play Contact us Sign in. Sudoku X Wing. Previous page. X Wing Take a look at row number 2 and row number 4 in this puzzle.

How to use x wing in sudoku

This idea is completely analogous, logically, to pairs, triplets, etc. Here is the idea as an X wing : Consider any one candidate Consider any two distinct rows Let the candidate be limited to no more than two cells in each of these two rows Let this group of no more than 4 cells share exactly two columns The candidate is forbidden from all the cells in those two columns outside of those 4 cells Because of symmetry, one can exchange columns for rows in this rule. Note the following: All possible locations for 3's in row 9 are f9,h9. All possible locations for 3's in row 5 are f5,h5. Forbids 3 from f4,f8,h4,h6.

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More Sudoku Tips:. Practical example In this example, the player would have a typical Sudoku X-Wing row pattern if the cells highlighted in orange did not have the number 5 as a candidate. The candidates that become impossible when answering both questions, can be safely removed. I know…that's a mouthful. Same thing with column 7 - it must have an 8 on R2 C7 or R4 C7. Home How to Play. The fins in this case will be the extra positions for the digit. Maybe not. Therefor we can eliminate 8 from all other cells in this column - R3 C7. There are more possible 8's in columns 5 and 7. Option 2 is the other way round. Is it a requirement that all four candidates be in four spearate boxes? What is interesting is the 7 s present elsewhere in the fourth and eighth columns.

The Sudoku X-Wing strategy is one of the most recurrent techniques that can be applied to Sudoku puzzles from a medium difficulty level onwards. It is a very straightforward technique with an easily identifiable pattern.

I have a puzzle in which all squares are filled except in the four boxes forming the x-wing. You will need to solve naked singles, hidden singles, a naked pair 4,7 in row 7, a locked candidate 5 in column 7, and a naked triple 2,4,5 in column 1 first. The yellow high lighted cells show the X-Wing formation. Unsolvable Sudoku Unsolvable Jigsaw New! We're Hey, Good Game , a tiny game studio that builds and buys games, for good. Starting from 2 rows and eliminating in 2 columns Starting from 2 columns and eliminating in 2 rows Starting from 2 boxes and eliminating in 2 rows Starting from 2 boxes and eliminating in 2 columns Starting from 2 rows and eliminating in 2 boxes Starting from 2 columns and eliminating in 2 boxes. The trick to understanding X-Wings is to imagine what would happen if you chose just one of those positions - what would it do to the others? Well, A and B are a locked pair of 7 s. If I am understanding this right, then the pattern can only be a square, rectangle, or trapezoid shape for any of these X-wing solutions. All the others can safely be eliminated. You gotta do these a few times to get an understanding. Appreciate any help.