Sudoku strategy
Swordfish Sudoku Strategy
Advanced technique Advanced
Swordfish extends X-Wing to three rows and three columns, locking a candidate into a larger line pattern.
How to use it
- Pick one candidate digit.
- Find three rows where that candidate appears only in two or three positions.
- Confirm the candidate positions fall within the same three columns.
- Remove the candidate from other cells in those columns.
- Check the reversed column-to-row version too.
Practice: Swordfish is uncommon, so use Expert or Evil puzzles and only search for it after easier techniques are exhausted.
Practice this strategy
Use the interactive solver to practice this technique on a fresh puzzle. If you get stuck, the Human Solve mode can show the next logical step.