Swordfish Sudoku Technique: How to Spot and Use It Step by Step
Sudoku a Day Blog ·
This PT-BR variant is live for indexing and locale coverage.
A fully localized long-form edition is planned; meanwhile you can use this page and the linked resources below.
Swordfish workflow
- Pick one digit and scan rows (or columns) only.
- Find exactly three rows where the candidate appears in two or three cells.
- Verify those candidates align to exactly three columns total.
- Eliminate that digit from other cells in those three columns.
Common mistakes to avoid
- Mixing row-based and column-based Swordfish scans in the same step.
- Forcing a pattern when candidates occupy more than three lines.
- Eliminating inside the pattern cells instead of outside them.
FAQ
When should I use Swordfish in Sudoku?
Use Swordfish after singles, locked candidates, and simpler pair/triple techniques are exhausted on hard or expert puzzles.
Is Swordfish just a bigger X-Wing?
Yes. X-Wing uses two lines and two columns; Swordfish extends the same logic to three lines and three columns.