XV数独
5
9
3
4
3
2
5
1
7
9
4
7
4
3
6
2
5
8
6
3
5
7
4
4
8
7
3
9
3
7
2
8
6
1
3
9
2
8
单元格之间的X表示它们之和为10；V表示它们之和为5
什么是XV数独？
XV Sudoku（也称为Ten-Five Sudoku）在相邻单元格之间放置X和V标记。X表示两个单元格之和为10；V表示它们之和为5。许多XV谜题使用负约束：没有标记保证这对数字之和既不是10也不是5。结合标准数独，这在整个网格中提供了非常严格的约束。
一览
| 约束类型 | 单元格关系 |
| 典型给定数 | 18–24 |
| 难度评级 | ★★★☆☆ 3/5 |
| 平均解题时间 — 简单 | 8 分钟 |
| 平均解题时间 — 中等 | 18 分钟 |
| 平均解题时间 — 困难 | 35 分钟 |
| 平均解题时间 — 专家 | 62 分钟 |
如何解XV数独
| 技巧 | 它的作用 | 级别 |
|---|---|---|
| Negative Constraint | Where no X or V appears between adjacent cells, their sum is neither 10 nor 5. This eliminates (1,9), (2,8), (3,7), (4,6) for X and (1,4), (2,3) for V. | 高级 |
| Sum Pair Enumeration | List all digit pairs that sum to 10 (for X) or 5 (for V), then use row/column placement to identify which pair must occupy each marked pair. | 高级 |
| Marker Chain Logic | Multiple consecutive X and V markers in a row form a sum chain — enumerate valid assignments for the entire chain simultaneously. | 高级 |
| Box X-Interaction | An X pair forces both digits into specific positions within their shared box, constraining all remaining cells of that box. | 高级 |
平均解题时间
简单
8 分钟
中等
18 分钟
困难
35 分钟
专家
62 分钟
常见问题
什么是XV数独？
XV Sudoku is a variant where X and V symbols appear between adjacent cells. An X marks two cells that sum to 10. A V marks two cells that sum to 5. Standard Sudoku rules apply, and — critically — all X and V relationships are fully marked: if there is no symbol between two adjacent cells, those cells are guaranteed not to sum to either 10 or 5.
What pairs sum to 10 (X)?
The valid X pairs are: 1&9, 2&8, 3&7, 4&6. Note that 5&5 sums to 10 but standard Sudoku uniqueness rules prevent two 5s from being adjacent in most cases. The X constraint immediately limits each marked cell to a small set of candidates.
What pairs sum to 5 (V)?
The valid V pairs are: 1&4, 2&3. Only four digits can ever appear in a V cell: 1, 2, 3, or 4. This makes V markers particularly powerful for restricting candidates in the lower half of the digit range.
How does the no-symbol constraint work?
All X and V relationships are shown — if two adjacent cells have no symbol, their sum is guaranteed to be neither 5 nor 10. This negative constraint eliminates candidate pairs from unmarked cell boundaries and is often as useful as the explicit symbols.
Is XV Sudoku hard to learn?
The rules are simple to memorise. The challenge is applying both the positive (X, V) and negative (no symbol) constraints simultaneously across the entire grid. Easy puzzles are very accessible; expert puzzles require exhaustive tracking of all adjacent-cell relationships.
How long does XV Sudoku take to solve?
Easy puzzles take 8–15 minutes. Medium puzzles run 15–30 minutes. Hard puzzles average 30–60 minutes and expert puzzles often exceed 90 minutes. The no-symbol negative constraint is the most time-consuming to apply systematically across a densely marked grid.