Sudoku X Wing Strategy
How to identify sudoku x wing.
Sudoku x wing strategy. These rules are useful for solving the really difficult sudoku puzzles when all else has been tried and failed. In looking for twins and permutations we restricted ourselves to looking at possibilities within a single group. X wing sudoku puzzle solving guide step. From the start in this second example i ve chosen a sudoku puzzle where an enormous number of candidates can be removed using two x wings.
F or generation and solution of sudoku puzzles download and install sudoku dragon. Load example or. It s an advanced strategy for sure. In this article i use one of my hand crafted very difficult puzzles that has a known x wing pattern.
After you have tried all the easier strategies and find no new squares to solve you can start looking for x wings in the puzzle. A sudoku x wing pattern occurs in many of the more difficult sudoku puzzles. X wing tutorial diagram1 x wing column sudoku strategy diagram 2 now shows where i have managed to fill in cells by a process of elimination and also my pencilled notations where i have been unable to whittle the answer down to a definitive number and so shows a number of possible candidates. Load example or.
If you haven t mastered the x wing strategy yet you ll likely find this strategy frustrating and possibly useless. The yellow high lighted cells show the x wing formation. Your ability to identify and solve this pattern will often break the logjam and lead you to the solution of a challenging sudoku game. The first three are pictured here but you can load the puzzle into the solver to see the remaining examples.
The x wing pattern appears in tricky sudoku puzzles when two rows or columns contain just two cells that hold matching candidates. The first is a 2 wing. Image via learn sudoku. While this strategy is not actually useless it is something that s hard to spot when you re looking at potential numbers for your cells.
X wing example 2. One of the more complex sudoku strategies is the x wing and its cousin the swordfish. X wing is a strategy in which you find a candidate that appears twice in two different rows and those appearances are both in the same column or the candidate appears twice in two different columns and those appearances are both in the same row.