What is the X-Wing technique in Sudoku?

X-Wing is an elimination technique where a candidate digit appears in exactly two cells in each of two rows (or columns), and those cells share the same two columns (or rows). This allows you to eliminate that digit from all other cells in those shared columns (or rows).

When should I use X-Wing in Sudoku?

Use X-Wing after exhausting singles, locked candidates, and naked/hidden pairs. It is typically needed on expert and master difficulty puzzles where simpler techniques run out.

What is the difference between a row-based and column-based X-Wing?

A row-based X-Wing scans two rows and eliminates the candidate from the two shared columns. A column-based X-Wing scans two columns and eliminates from the two shared rows. Both work by the same logic; the choice depends on where the pattern appears.

Does X-Wing work on all Sudoku difficulty levels?

X-Wing is rarely needed on easy or medium puzzles. It appears most often on expert and master grids. If you are just starting with advanced techniques, X-Wing is a good first step before Swordfish.

Tecnica X-Wing nel Sudoku: come individuarla e usarla

Sudoku a Day Blog · 2026-03-15

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