Sandwich數獨
0
27
25
0
0
0
17
9
8
22
12
9
0
8
9
16
6
11
5
8
1
2
6
4
3
7
9
5
1
3
6
9
9
6
9
4
8
7
5
9
7
6
2
5
9
7
2
6
5
1
9
8
3
4
5
7
線索給出每行/列中1和9之間數字的和
什麼是 Sandwich數獨？
三明治數獨將提示放置在網格外部。每個提示給出該行或列中擠在1和9之間的所有數字的和。1和9的位置各異，因此「三明治」可以有0到7個單元格，取決於它們的位置。提示為0表示1和9相鄰。提示為35表示所有數字2–8都在它們之間。
一覽
| 約束類型 | 外部線索 |
| 典型給定數字 | 4–10 clue values |
| 難度評級 | ★★★★☆ 4/5 |
| 平均解題時間 — 簡單 | 12 分鐘 |
| 平均解題時間 — 中等 | 26 分鐘 |
| 平均解題時間 — 困難 | 52 分鐘 |
| 平均解題時間 — 專家 | 85 分鐘 |
如何解 Sandwich數獨
| 技巧 | 它的作用 | 等級 |
|---|---|---|
| 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. | 進階 |
| 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. | 進階 |
| 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. | 進階 |
| Sandwich Intersection | Row and column clues intersect at one cell. Combining row positions of 1 and 9 with column positions pinpoints key placements. | 進階 |
| Digit Forcing from Both Sides | Use clues from both the row and column sides to triangulate the positions of 1 and 9 simultaneously. | 進階 |
平均解題時間
簡單
12 分鐘
中等
26 分鐘
困難
52 分鐘
專家
85 分鐘
每日三文治數獨
常見問題
乜嘢係Sandwich Sudoku？
Sandwich Sudoku is a variant where clue numbers appear outside the grid, one per row and one per column. Each clue tells you the sum of all digits that appear between the 1 and the 9 in that row or column. Standard Sudoku rules apply throughout.
How do I use the sandwich clues?
First, find the positions of the 1 and 9 in each row or column — every other digit between them must sum to the outside clue. A clue of 0 means the 1 and 9 are adjacent. A clue equal to the maximum possible sum (e.g., 35 for a 7-cell sandwich) tells you the 1 and 9 are at the ends. Work from the most constrained clues first.
三明治線索0是什麼意思？
A clue of 0 means no digits are sandwiched between the 1 and 9 — they must be directly adjacent to each other. This is one of the most powerful clues because it immediately tells you where 1 and 9 can and cannot be placed relative to each other in that row or column.
Is Sandwich Sudoku harder than regular Sudoku?
Yes, generally. Sandwich Sudoku provides very few pre-filled digits inside the grid. Almost all deductions flow from working out where 1 and 9 can sit and what sums are achievable. The logic is more algebraic than classic Sudoku, which many players find both more challenging and more satisfying.
Can the 1 and 9 be at the ends of a row?
Yes. If the 1 is in column 1 and the 9 is in column 9 (or vice versa), the sandwiched digits are columns 2–8, giving a maximum possible sum of 2+3+4+5+6+7+8 = 35. Extreme clue values like this immediately fix the positions of both the 1 and the 9.
How long does Sandwich Sudoku take to solve?
Easy puzzles typically take 10–20 minutes. Medium puzzles run 20–35 minutes. Hard puzzles can take 45–75 minutes, and expert puzzles often exceed 90 minutes. The key bottleneck is working out 1/9 positions — once you pin those down, the rest of the grid often resolves quickly.