対角線数独
1
8
9
6
5
9
2
3
1
8
3
4
9
2
9
3
8
1
7
7
1
3
6
9
4
7
8
9
2
3
6
3
5
8
2
2
8
6
ダイアゴナル数独の遊び方
標準の数独ルールが適用されます：すべての行、列、3×3ボックスに1～9を配置します。追加ルール：強調表示された両方の対角線（↘および↙）にも各数字がちょうど1回ずつ含まれなければなりません。中央のセルは両方の対角線上にあり、盤上で最も制約の多いセルになります。
完全ガイド →
両方の主対角線も1〜9を含まなければなりません
対角線数独とは？
ダイアゴナル数独では、標準の9×9ルールが適用されますが、強力な追加の制約が1つあります。両方の主対角線（左上から右下、および右上から左下）は、それぞれ1から9までのすべての数字を1回ずつ含む必要があります。この追加の制約により、対角線が排除のための2つの追加ユニットとして機能するため、通常、パズルは解きやすくなります。
概要
| 制約タイプ | 追加領域 |
| 典型的な初期数字 | 22–28 |
| 難易度評価 | ★★☆☆☆ 2/5 |
| 平均解答時間 — 簡単 | 4分 |
| 平均解答時間 — ミディアム | 10分 |
| 平均解答時間 — 難しい | 20分 |
| 平均解答時間 — エキスパート | 40分 |
対角線数独 の解き方
| テクニック | それが何をするか | レベル |
|---|---|---|
| Diagonal as a Unit | Treat each diagonal exactly like a row or column — every digit 1–9 appears exactly once. Standard scanning and counting apply. | 上級 |
| Diagonal–Box Interaction | When a digit on a diagonal is confined to one box segment, eliminate it from the rest of that box. | 上級 |
| Diagonal Naked Pairs | If two cells on a diagonal share the same two candidates, eliminate those values from all other diagonal cells. | 上級 |
| Three-Unit Intersection | A cell on the main diagonal also belongs to a row, column, and box — four constraint units simultaneously — maximising elimination power. | 上級 |
平均解答時間
簡単
4分
ミディアム
10分
難しい
20分
エキスパート
40分
よくある質問
Diagonal Sudokuとは何ですか？
Diagonal Sudoku adds two extra constraints on top of standard Sudoku: both main diagonals of the 9×9 grid must each contain the digits 1–9 exactly once. This means every cell on either diagonal belongs to four uniqueness groups simultaneously: its row, column, box, and diagonal.
Which cells are on the diagonals?
The main diagonals run from the top-left corner to the bottom-right corner, and from the top-right corner to the bottom-left corner. Together they cover 17 cells (the centre cell is on both). Any cell at position (r, c) is on a diagonal if r equals c or if r + c equals 10 (using 1-based numbering).
How does the diagonal constraint help solving?
Diagonal cells carry four constraints instead of the usual three, making them the most restricted cells on the board. Whenever you place a digit anywhere on a diagonal, it eliminates that digit from the entire row, column, box, and the diagonal simultaneously — often triggering a cascade of placements.
Is Diagonal Sudoku harder than regular Sudoku?
At easy difficulty, Diagonal Sudoku is actually easier than equivalent classic Sudoku because the extra constraints eliminate more candidates immediately. At hard and expert levels, the diagonal interactions create subtler deductions that experienced players find more challenging to spot.
Can I solve Diagonal Sudoku using standard techniques?
Yes — all standard Sudoku techniques (naked pairs, hidden singles, pointing pairs, X-Wings, etc.) apply. You simply treat each diagonal as an additional house. The most important habit is scanning both diagonals after every placement, the same way you scan rows, columns, and boxes.
How long does Diagonal Sudoku take to solve?
Easy puzzles take 5–12 minutes — often faster than equivalent classic puzzles because of the extra constraints. Medium puzzles run 12–25 minutes. Hard and expert puzzles can take 30–70 minutes depending on how heavily the diagonal interactions need to be exploited.