困難外圍數獨
網格外側的提示給出該行或列中遇到的前三個數字——但不包含順序。
困難 外部數獨。較少的邊界線索和更緊密的互動——預期多步驟推導和仔細的 筆記 工作。
7
5
9
5
9
2
7
1
8
5
3
4
8
3
1
7
9
4
7
4
2
6
8
7
6
4
6
3
5
8
9
3
7
6
5
2
7
3
2
9
3
5
6
1
2
8
4
7
3
5
8
8
7
5
6
4
3
6
8
1
4
9
5
什麼是 外部數獨？
難度
★★★☆☆
3/5
約束類型
外部線索
典型給定數
28–36 given + 4×9 outside clues
平均解題時間（困難）
36分鐘
解題技巧：困難 等級
| 技巧 | 描述 | 等級 |
|---|---|---|
| Clue-Zone Mapping | Each outside digit must appear in the nearest 3 cells of its row or column. Map all outside clues to their zones immediately. | 初學者 |
| Cross-Side Reasoning | If left clue digit X must be in cols 1–3, and right clue digit X is in the same row, that row already places X — the other side confirms its column. | 中級 |
| Box-Side Interaction | An outside clue for a row interacts with the box containing cols 1–3. If the row's box is heavily constrained, the outside digit's position may be forced. | 中級 |
| Digit Elimination from Clues | When a clue digit is placed in the zone, eliminate it from the rest of the zone row/col using standard Sudoku logic. | 中級 |
| Dual-Side Chains | Combine left and right clues for the same row: both digits restrict the same three columns from opposite ends, leaving the middle box fully determined. | 進階 |
準備好終極測試了嗎？試試 專家 外部數獨 — 數獨 上最難的謎題。
在 困難 需要掌握的技巧
- Hidden Pairs technique — Opposite-side clues squeeze a row from both ends, stripping middle candidates — recount the centre box of heavily-clued rows, where hard outside grids hide their pairs.
- X-Wing 技巧 — Clue windows fix which third of each line a digit occupies; when two rows confine a digit to the same two columns inside their windows, the X-Wing clears both columns.
依難度平均解題時間
簡單
8分鐘
中等
18分鐘
困難
36分鐘
專家
65分鐘
想要規則、策略和解題步驟的完整演練嗎？
如何遊玩 外部數獨 →
相關變體
Skyscraper數獨
The next step in border-clue logic — outside numbers become visibility counts that constrain entire row orderings.
Sandwich數獨
Border clues with arithmetic teeth: each one is the sum of the digits trapped between 1 and 9.
殺手數獨
Moves the clue layer inside the grid as summed cages — a natural graduation from window placement to sum deduction.
常見問題 — 困難 外部數獨
還有問題？請參閱完整 外部數獨指南.