Sandwich Sudoku
Clues give the sum of digits between the 1 and 9 in each row/column
Easy
Sandwich Sudoku Easy
Medium
Sandwich Sudoku Medium
Hard
Sandwich Sudoku Hard
Expert
Sandwich Sudoku Expert
What is Sandwich Sudoku?
Sandwich Sudoku places clues along the outside of the grid. Each clue gives the sum of all digits squeezed between the 1 and the 9 in that row or column. The positions of 1 and 9 vary, so the 'sandwich' can have 0 to 7 cells depending on where they land. A clue of 0 means 1 and 9 are adjacent. A clue of 35 means all digits 2–8 are between them.
At a Glance
| Constraint type | Outside Clues |
| Typical givens | 4–10 clue values |
| Difficulty rating | ★★★★☆ 4/5 |
| Avg. solve time — Easy | 12 min |
| Avg. solve time — Medium | 26 min |
| Avg. solve time — Hard | 52 min |
| Avg. solve time — Expert | 85 min |
How to Solve Sandwich Sudoku
| Technique | What it does | Level |
|---|---|---|
| Clue 0 Means Adjacent 1 and 9 | A sandwich clue of 0 means 1 and 9 are side-by-side with nothing between them. Place this pair immediately. | Beginner |
| Clue 35 Means 1 and 9 at Ends | A clue of 35 = 2+3+4+5+6+7+8. All middle digits are sandwiched, placing 1 and 9 at the two ends of the row/column. | Beginner |
| Position Enumeration | For each clue, enumerate all valid positions of 1 and 9 such that the enclosed digits sum to the clue. Cross-reference with column clues. | Intermediate |
| Sandwich Intersection | Row and column clues intersect at one cell. Combining row positions of 1 and 9 with column positions pinpoints key placements. | Advanced |
| Digit Forcing from Both Sides | Use clues from both the row and column sides to triangulate the positions of 1 and 9 simultaneously. | Intermediate |
Average Solve Times
Easy
12 min
Medium
26 min
Hard
52 min
Expert
85 min
Frequently Asked Questions
What digits are 'sandwiched'?
All digits strictly between the 1 and the 9 in that row or column. The 1 and 9 themselves are not counted.
Can 1 and 9 swap positions?
Yes — the clue refers to digits between them regardless of which comes first.
What if the clue has multiple configurations?
Multiple arrangements may satisfy a single clue — use cross-row/column constraints to eliminate the extras.