回文 Sudoku
8
2
3
1
4
1
5
5
4
9
7
6
7
2
2
1
7
9
9
5
1
8
2
7
9
4
5
6
4
1
2
8
6
2
7
1
9
4
パリンドローム数独の遊び方
標準数独ルールが適用されます。各灰色の線は回文です - 数字の並びが両端から同じに読めます。5セルの線が3,7,5,7,3と読む場合、位置1 = 位置5、位置2 = 位置4。
完全ガイド →
ラインに沿った数字の並びは、前から読んでも後ろから読んでも同じです。
回文 Sudokuとは？
パリンドローム数独は、数字の並びがパリンドロームでなければならない線をグリッド上にマークします — 両方向から読んで同じになります。線がセルA-B-C-D-Eを持つ場合、A=E、B=Dであり、Cは中央の数字です。これにより、同じ値を共有しなければならないセルのペアが作成され、グリッド全体に強力な等価制約として機能します。
概要
| 制約タイプ | ライン制約 |
| 典型的な初期数字 | 20–28 |
| 難易度評価 | ★★★☆☆ 3/5 |
| 平均解答時間 — 簡単 | 7分 |
| 平均解答時間 — ミディアム | 16分 |
| 平均解答時間 — 難しい | 32分 |
| 平均解答時間 — エキスパート | 58分 |
回文 Sudoku の解き方
| テクニック | それが何をするか | レベル |
|---|---|---|
| Mirror Pair Identification | In a palindrome of length L, cell i and cell L+1−i must share the same digit. Identify all mirror pairs before solving. | 上級 |
| Centre Cell Freedom | The central cell of an odd-length palindrome has no mirror constraint — it is only restricted by standard row/column/box rules. | 上級 |
| Mirror Propagation | Once one cell of a mirror pair is determined, immediately set its partner to the same value. | 上級 |
| Multi-Palindrome Intersection | If two palindromes share a cell, that cell must satisfy both palindrome relationships simultaneously. | 上級 |
平均解答時間
簡単
7分
ミディアム
16分
難しい
32分
エキスパート
58分
よくある質問
Palindrome Sudokuとは何ですか？
Palindrome Sudoku is a variant where grey lines are drawn across the grid. Every grey line must read the same forwards and backwards — meaning the first cell mirrors the last, the second mirrors the second-to-last, and so on. Standard Sudoku rules apply throughout.
How does the palindrome constraint work?
For any palindrome line, cell positions are mirrored around the centre. On a 6-cell line, cells 1 and 6 hold the same digit, cells 2 and 5 hold the same digit, and cells 3 and 4 hold the same digit. This immediately links distant parts of the grid — placing a digit at one end fixes the digit at the other end.
Can palindrome lines have repeated digits?
Yes, palindrome lines inherently require digit repetition — each mirrored pair shares the same digit. However, standard Sudoku rules still apply, so a repeated digit must be in different rows, columns, and boxes. Palindrome lines are carefully constructed so that this repetition is always consistent with uniqueness rules.
Is Palindrome Sudoku harder than regular Sudoku?
Easy palindrome puzzles are often easier than classic Sudoku because the mirroring immediately links cells across the board, providing extra deductions. Harder difficulties become quite challenging because you must track mirrored constraints across long lines while maintaining standard Sudoku logic.
What is the best first move in Palindrome Sudoku?
Find palindrome lines where one endpoint cell is already constrained by its row, column, or box. Placing a digit there immediately fixes the mirrored cell at the other end. Also look for odd-length lines — the centre cell has no mirror partner, so it's only constrained by standard Sudoku rules.
How long does Palindrome 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 difficulty increases sharply when multiple long palindrome lines overlap across the same region of the grid.