Medium Between Lines Sudoku
Ready to sharpen your skills? Medium Between Lines Sudoku puzzles introduce interactions between the variant constraint and classic Sudoku techniques. You'll need to combine both skill sets to progress.
What to expect at Medium level
Medium Between Lines Sudoku puzzles require you to combine the variant constraint with standard Sudoku deduction - Naked pairs, hidden singles, and unit scans. The constraint is more tightly woven into the grid, so you'll need to think a few steps ahead.
Best suited for players comfortable with Easy Between Lines Sudoku who want to build their pattern recognition.
Difficulty overview
About Between Lines Sudoku
Between Lines Sudoku draws lines with circular endpoints. Every digit along the line (excluding the endpoints themselves) must be strictly greater than the smaller endpoint and strictly less than the larger endpoint. If the endpoints are 2 and 8, every middle cell on the line must be one of 3, 4, 5, 6, or 7. The closer the endpoints are in value, the more constrained the middle cells.
Solving Techniques for Medium Level
| Technique | Description | Level |
|---|---|---|
| Endpoint Gap Analysis | The gap between endpoint values must be large enough to accommodate all middle cells. If endpoints are 2 and 8, middle cells must come from {3,4,5,6,7}. | Beginner |
| Endpoint Ordering | The endpoint values have no fixed order — the constraint is that all middle cells are strictly between the minimum and maximum endpoint. | Beginner |
| Tight Endpoint Constraint | If endpoints would be consecutive (e.g., 3 and 4), no middle cell could satisfy the strict inequalities — use this to force endpoints apart. | Intermediate |
Master these, then take on Hard Killer Sudoku to learn Advanced techniques.