Palindrome Sudoku
The digit sequence along a line reads the same forwards and backwards
Easy
Palindrome Sudoku Easy
Medium
Palindrome Sudoku Medium
Hard
Palindrome Sudoku Hard
Expert
Palindrome Sudoku Expert
What is Palindrome Sudoku?
Palindrome Sudoku marks lines on the grid whose digit sequence must be a palindrome — reading the same in both directions. If a line has cells A-B-C-D-E, then A=E and B=D, while C is the central digit. This creates pairs of cells that must share the same value, acting as powerful equality constraints across the grid.
At a Glance
| Constraint type | Line Constraints |
| Typical givens | 20–28 |
| Difficulty rating | ★★★☆☆ 3/5 |
| Avg. solve time — Easy | 7 min |
| Avg. solve time — Medium | 16 min |
| Avg. solve time — Hard | 32 min |
| Avg. solve time — Expert | 58 min |
How to Solve Palindrome Sudoku
| Technique | What it does | Level |
|---|---|---|
| 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. | Beginner |
| 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. | Beginner |
| Mirror Propagation | Once one cell of a mirror pair is determined, immediately set its partner to the same value. | Intermediate |
| Multi-Palindrome Intersection | If two palindromes share a cell, that cell must satisfy both palindrome relationships simultaneously. | Advanced |
Average Solve Times
Easy
7 min
Medium
16 min
Hard
32 min
Expert
58 min
Frequently Asked Questions
Does the line read the same in both directions?
Yes — reading the digits from either end gives the same sequence. Position 1 = position N, position 2 = position N−1, etc.
Can all nine digits appear on one palindrome?
Only if the palindrome has 9 cells. But mirror pairs mean at most 5 distinct values can appear on any palindrome.