Hard Non-Consecutive Sudoku
9
4
1
6
5
7
8
9
6
8
5
4
6
4
2
9
8
3
3
2
1
8
7
6
9
7
6
How to play Non-Consecutive Sudoku
Standard Sudoku rules apply. Extra rule: no two orthogonally adjacent cells (sharing an edge) may contain consecutive digits. If a cell holds 5, all four neighbours must avoid 4 and 6.
About Non-Consecutive Sudoku
Difficulty
★★★☆☆
3/5
Constraint Type
Anti-Constraints
Typical Givens
18–24
Avg. Solve (Medium)
13 min
Non-Consecutive Sudoku imposes a global constraint: no two cells that share an edge (orthogonally adjacent) can contain consecutive digits. So if a cell contains 5, all its neighbours must avoid 4 and 6. This single rule dramatically limits candidate placements and can reduce a standard givens count while still producing a uniquely solvable puzzle.
Solving Techniques
| Technique | Description | Level |
|---|---|---|
| Global Candidate Pruning | For every filled cell, remove its ±1 neighbours from all orthogonally adjacent cells immediately. | Beginner |
| Digit 5 is Most Constrained | 5 cannot be adjacent to 4 or 6. Use this to restrict placement of 5 across the entire grid. | Intermediate |
| Chain Propagation | Placing a digit propagates constraints along rows and columns, often triggering a cascade of forced placements. | Intermediate |
| Forbidden Pair Maps | Build a map of forbidden digit pairs for each adjacent pair of cells and use it to eliminate candidates systematically. | Advanced |
Average Solve Time by Difficulty
Easy
5 min
Medium
13 min
Hard
26 min
Expert
48 min