Non-Consecutive Sudoku
No two orthogonally adjacent cells may contain consecutive digits
Easy
Non-Consecutive Sudoku Easy
Medium
Non-Consecutive Sudoku Medium
Hard
Non-Consecutive Sudoku Hard
Expert
Non-Consecutive Sudoku Expert
What is Non-Consecutive Sudoku?
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.
At a Glance
| Constraint type | Anti-Constraints |
| Typical givens | 18–24 |
| Difficulty rating | ★★★☆☆ 3/5 |
| Avg. solve time — Easy | 5 min |
| Avg. solve time — Medium | 13 min |
| Avg. solve time — Hard | 26 min |
| Avg. solve time — Expert | 48 min |
How to Solve Non-Consecutive Sudoku
| Technique | What it does | 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 Times
Easy
5 min
Medium
13 min
Hard
26 min
Expert
48 min
Frequently Asked Questions
Which cells count as 'adjacent'?
Only orthogonally adjacent cells — sharing an edge horizontally or vertically. Diagonal neighbours are unaffected.
Is same-digit adjacency also forbidden?
Same-digit adjacency is already forbidden by standard row/column/box rules — non-consecutive only additionally forbids digits differing by exactly 1.