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The following Jigsaw Sudoku Puzzle was generated in Feb, 2024
using 1to9only new release of SudokuExplainer.
The puzzle is rated SER = 8.0, and it can be solved (manually) in
four main steps.
(image created using SudokuExplainer)
(EDIT: Feb 14, 2025)
After basics, one should reach the following configuration
+-----------------------------+----------+------------------------------------------------------+
| 47 2 47 | 1369 | 136 136 169 5 8 | 9
| | +---------------------+ |
| 1368 5 1368 | 13689 13468 13468 | 7 12369 1239 | 8
| +------------------+---------------------+ +---------------------+ |
| 138 | 6 23578 2358 9 | 123578 125 12378 | 4 | 7
| +-------+ +---------------------+---------------------+ +----------+
| 1368 9 | 234578 | 123568 12345678 12345678 1245 | 123678 12357 | 6
+------------------+ +----------+ +---------------------+---------------------+
| 47 1 24578 258 | 245678 | 2568 3 2689 259 | 5
+------------------+---------------------+ +----------+ +---------------------+
| 1258 7 | 9 123568 123568 123568 | 1256 | 4 1235 | 4
+----------+ +---------------------+---------------------+ +----------+ |
| 9 | 3 1258 1258 | 124578 124578 1245 1278 | 6 | 3
| +------------------+ +---------------------+---------------------+ |
| 1235 8 1235 | 4 1256 1256 | 1259 12379 123579 | 2
| +---------------------+ | |
| 12356 4 12356 7 12356 | 9 | 8 123 1235 | 1
+---------------------------------------------------+----------+--------------------------------+
a b c d e f g h i
Update 2 (Jun 6, 2025)
For Step 1:
+-----------------------+----------+------------------------------------------------+
|*47 2 *47 | 1369 | 136 136 169 5 8 | 9
| | +---------------------+ |
| 1368 5 1368 | 13689 13468 13468 | 7 12369 1239 | 8
| +---------------+---------------------+ +-----------------+ |
| 138 | 6 23578 2358 9 | 123578 125 12378 | 4 | 7
| +-----+ +---------------------+-------------------+ +--------+
| 1368 9 | 234578 | 123568 12345678 12345678 1245 | 123678 12357 | 6
+-------------+ +----------+ +-------------------+-----------------+
|*47 1 *24578 258 | 47-2568 | 2568 3 2689 259 | 5
+-------------+--------------------+ +----------+ +-----------------+
| 1258 7 | 9 123568 123568 123568 | 1256 | 4 1235 | 4
+-------+ +--------------------+---------------------+ +--------+ |
| 9 | 3 1258 1258 | 124578 124578 1245 1278 | 6 | 3
| +---------------+ +---------------------+-----------------+ |
| 1235 8 1235 | 4 1256 1256 | 1259 12379 123579 | 2
| +---------------------+ | |
| 12356 4 12356 7 12356 | 9 | 8 123 1235 | 1
+---------------------------------------------+----------+--------------------------+
a b c d e f g h i
UR(47) ac59 => -2568 e5 [& basics]
----
For Step 2:
+----------------------------+---------+------------------------------------------------+
| 47 2 47 | 9 | 13 13 6 5 8 | 9
| | +--------------------+ |
| 1368 5 1368 | 1368 13468 13468 | 7 9 2 | 8
| +-----------------+--------------------+ +-------------------+ |
| 138 | 6 B(7)38 38 9 | 25 25 A(7)138 | 4 | 7
| +-------+ +--------------------+-------------------+ +-------+
| 1368 9 | 234578 | 12358 1234578 E(7)123458 1245 | 13678 137 | 6
+------------------+ +---------+ +-------------------+-----------------+
|C(7)4 1 258 258 |D(7)4 | 2568 3 68 9 | 5
+------------------+-------------------+ +---------+ +-----------------+
| 1258 7 | 9 123568 123568 123568 | 125 | 4 135 | 4
+----------+ +-------------------+--------------------+ +---------+ |
| 9 | 3 1258 1258 | 124578 F(7)12458 1245 18-7 | 6 | 3
| +-----------------+ +--------------------+-------------------+ |
| 1235 8 1235 | 4 1256 1256 | 9 1237 1357 | 2
| +--------------------+ | |
| 12356 4 12356 7 12356 | 9 | 8 123 135 | 1
+-------------------------------------------------+---------+---------------------------+
a b c d e f g h i
2. (7)h7 = (7)c7 - (7)a5 = (7)e5 - (7)f6 = (7)f3 => -7 h3
Now, it remains to find two wings starting in the following configuration
+---------------------------+---------+----------------------------------------------+
| 47 2 47 | 9 | 13 13 6 5 8 | 9
| | +-------------------+ |
| 1368 5 1368 | 1368 13468 13468 | 7 9 2 | 8
| +----------------+-------------------+ +-------------------+ |
| 138 | 6 378 38 9 | 25 25 1378 | 4 | 7
| +------+ +-------------------+-------------------+ +------+
| 1368 9 | 234578 | 12358 1234578 1234578 1245 | 13678 137 | 6
+-----------------+ +---------+ +-------------------+----------------+
| 47 1 258 258 | 47 | 2568 3 68 9 | 5
+-----------------+-------------------+ +---------+ +----------------+
| 1258 7 | 9 123568 123568 123568 | 125 | 4 135 | 4
+----------+ +-------------------+-------------------+ +---------+ |
| 9 | 3 1258 1258 | 124578 124578 1245 18 | 6 | 3
| +----------------+ +-------------------+-------------------+ |
| 1235 8 1235 | 4 1256 1256 | 9 1237 1357 | 2
| +-------------------+ | |
| 12356 4 12356 7 12356 | 9 | 8 123 135 | 1
+-----------------------------------------------+---------+--------------------------+
a b c d e f g h i
On this occasion (one year of this Website),
I propose the following Jigsaw Sudoku puzzle.
(found with JigsawExplainer)
After many basics moves, one should get the following configuration:
+-----------------------+-------+---------------------------------------+
| 3579 4 1 | 359 | 589 589 2 6 37 | 9
| | +---------------+ +-------+ |
| 8 357 359 | 6 1 2 | 59 | 4 | 37 | 8
| +---------------+---------------+ +-------+ | |
| 359 | 2 6 4 7 | 359 589 589 | 1 | 7
| +-------+ +---------------+---------------+ | |
| 2 6 | 58 | 3589 3589 1 358 | 7 | 4 | 6
+---------------+ +-------+ +---------------+-------+-------+
| 1 9 358 358 | 4 | 7 6 2 | 58 | 5
+---------------+---------------+ +-------+ +-------+ |
| 4 358 | 7 2 58 6 | 3589 | 1 589 | 4
+-------+ +---------------+---------------+ +-------+ |
| 3569 | 578 2 35789 | 358 4 1 589 | 5689 | 3
| +---------------+ +---------------+-------+ | |
| 359 358 4 | 1 6 359 | 7 | 589 | 2 | 2
| +---------------+ | +-------+ |
| 5679 1 589 578 2 | 589 | 4 3 5689 | 1
+---------------------------------------+-------+-----------------------+
a b c d e f g h i
Update (Feb 16, 2025): This puzzle can be solved in three steps.
For step 1, one can look at the pattern of 3s in the grid
and find an extended M-wing that eliminates (7)b8 and gives 7 placements.
After this step and resulting placements, one should get
+---------------------+------+------------------------------------+ | 7 4 1 | 59 | 589 589 2 6 3 | 9 | | +-------------+ +-------+ | | 8 35 359 | 6 1 2 | 59 | 4 | 7 | 8 | +-------------+-------------+ +-------+ | | | 59 | 2 6 4 7 | 3 589 589 | 1 | 7 | +------+ +-------------+--------------+ | | | 2 6 | 58 | 3589 3589 1 358 | 7 | 4 | 6 +--------------+ +------+ +--------------+-------+------+ | 1 9 358 358 | 4 | 7 6 2 | 58 | 5 +--------------+-------------+ +------+ +-------+ | | 4 358 | 7 2 58 6 | 3589 | 1 589 | 4 +-------+ +-------------+-------------+ +-------+ | | 569 | 7 2 3589 | 358 4 1 589 | 5689 | 3 | +-------------+ +-------------+-------+ | | | 3 58 4 | 1 6 59 | 7 | 589 | 2 | 2 | +-------------+ | +-------+ | | 569 1 589 7 2 | 589 | 4 3 5689 | 1 +-----------------------------------+------+----------------------+ a b c d e f g h i
For step 2, one can search for an ALS M-wing that eliminates (9)h7.
No placement or further elimination takes place
(i.e., one can look at the previous grid withoug (9)h7 for the next move).
After -9 h7, there is an almost W-wing that solves the puzzle.
Update (Feb 17, 2025): all moves for the 3-step solution follow
After basics
+-------------------------+-------+---------------------------------------+
|c(3)579 4 1 | 359 | 589 589 2 6 37 | 9
| | +---------------+ +-------+ |
| 8 b(3)5-7 b(3)59 | 6 1 2 | 59 | 4 |a(37) | 8
| +----------------+---------------+ +-------+ | |
|c(3)59 | 2 6 4 7 | 359 589 589 | 1 | 7
| +--------+ +---------------+---------------+ | |
| 2 6 | 58 | 3589 3589 1 358 | 7 | 4 | 6
+-----------------+ +-------+ +---------------+-------+-------+
| 1 9 358 358 | 4 | 7 6 2 | 58 | 5
+-----------------+---------------+ +-------+ +-------+ |
| 4 f(3)58 | 7 2 58 6 | 3589 | 1 589 | 4
+--------+ +---------------+---------------+ +-------+ |
|d(3)569 |h(7)58 2 g(37)589| 358 4 1 589 | 5689 | 3
| +----------------+ +---------------+-------+ | |
|d(3)59 e(3)58 4 | 1 6 f(3)59 | 7 | 589 | 2 | 2
| +---------------+ | +-------+ |
| 5679 1 589 578 2 | 589 | 4 3 5689 | 1
+-----------------------------------------+-------+-----------------------+
a b c d e f g h i
1. (7=3)i8 - (3)b8.c8 = (3)a7.a9 - (3)a2.a3 = (3)b2 - (3)b4|f2 = (3-7)d3 = (7)b3
=> -7 b8 [7 placements and LC elimination]
------
+---------------------+------+------------------------------------+
| 7 4 1 | 59 | 589 589 2 6 3 | 9
| | +-------------+ +-------+ |
| 8 b(35) 359 | 6 1 2 | 59 | 4 | 7 | 8
| +-------------+-------------+ +-------+ | |
|a(59) | 2 6 4 7 | 3 589 58-9 | 1 | 7
| +------+ +-------------+--------------+ | |
| 2 6 | 58 | 3589 3589 1 358 | 7 | 4 | 6
+--------------+ +------+ +--------------+-------+------+
| 1 9 358 358 | 4 | 7 6 2 | 58 | 5
+--------------+-------------+ +------+ +-------+ |
| 4 c(3)58 | 7 2 58 6 |d(39)58| 1 589 | 4
+-------+ +-------------+-------------+ +-------+ |
| 569 | 7 2 3589 | 358 4 1 e(9)58 | 5689 | 3
| +-------------+ +-------------+-------+ | |
| 3 58 4 | 1 6 59 | 7 |e(9)58 | 2 | 2
| +-------------+ | +-------+ |
| 569 1 589 7 2 | 589 | 4 3 5689 | 1
+-----------------------------------+------+----------------------+
a b c d e f g h i
2. (9=5)a7 - (5=3)b8 - (3)b4 = (3-9)g4 = (9)h2.h3 => -9 h7
------
+---------------------+------+----------------------------------+
| 7 4 1 | 59 | 589 589 2 6 3 | 9
| | +-------------+ +------+ |
| 8 #(5)3 {59}3 | 6 1 2 | 59 | 4 | 7 | 8
| +-------------+-------------+ +------+ | |
|#[5]9 | 2 6 4 7 | 3 589 [58] | 1 | 7
| +------+ +-------------+-------------+ | |
| 2 6 | 58 | 3589 3589 1 358 | 7 | 4 | 6
+--------------+ +------+ +-------------+------+------+
| 1 9 358 358 | 4 | 7 6 2 | 58 | 5
+--------------+-------------+ +------+ +------+ |
| 4 358 | 7 2 58 6 | 3958 | 1 589 | 4
+-------+ +-------------+-------------+ +------+ |
| 569 | 7 2 3589 | 358 4 1 958 | 5689 | 3
| +-------------+ +-------------+------+ | |
| 3 #[5{8}] 4 | 1 6 59 | 7 | 95-8 | 2 | 2
| +-------------+ | +------+ |
| 569 1 {98}5 7 2 | 589 | 4 3 5689 | 1
+-----------------------------------+------+--------------------+
a b c d e f g h i
3. Almost W-wing [(8=5)h7 - (5)a7 = (5)b8 - (5=8)b2]
(8)b2 = (8-9)c1 = (9-5)c8 = W-wing => -8 h2; ste
In words: either we have the W-wing at the (#)-marked cells, or
(5)c8 is true, but in this case we must have (9)c1 and (8)b2.
So, in any case, (8)h2 is eliminated.
EDIT (Feb 18, 2025): changed notation of moves to chess notation
and added comment on the meaning of the last move.
How to solve (manually) this puzzle in just one step ?
(generated with 1to9only release of SudokuExplainer)
After basics, one should reach the following configuration
+--------------------+------+----------------------------------+
| 5 47 8 | 9 | 124 147 3 6 127 | 9
| | +-------------+ +------+ |
| 9 3 6 | 147 124 8 | 457 | 1247 | 57 | 8
| +-------------+-------------+ +------+ | |
| 1 | 457 2 457 8 | 6 57 3 | 9 | 7
| +------+ +-------------+-------------+ | |
| 47 2 | 57 | 6 3 9 1 | 457 | 8 | 6
+-------------+ +------+ +-------------+------+------+
| 6 1 9 3 | 7 | 5 2 8 | 4 | 5
+-------------+-------------+ +------+ +------+ |
| 3 9 | 4 8 5 2 | 6 | 17 17 | 4
+------+ +-------------+-------------+ +------+ |
| 2 | 8 157 457 | 14 3 47 9 | 6 | 3
| +-------------+ +-------------+------+ | |
| 8 457 157 | 2 6 47 | 9 | 147 | 3 | 2
| +-------------+ | +------+ |
| 47 6 3 147 9 | 147 | 8 25 25 | 1
+----------------------------------+------+--------------------+
a b c d e f g h i
One way to find a move that solves the puzzle is to look at the patterns of 5 and 7.
In particular, the strong links (7)g3 = (7)h2 and (5)g7 = (5)h6.
Final Update: Jun 13, 2025
+--------------------+------+----------------------------------+
| 5 47 8 | 9 | 124 147 3 6 127 | 9
| | +-------------+ +------+ |
| 9 3 6 | 147 124 8 | 457 | 1247 |(5)-7 | 8
| +-------------+-------------+ +------+ | |
| 1 | 457 2 457 8 | 6 (57) 3 | 9 | 7
| +------+ +-------------+-------------+ | |
| 47 2 | 57 | 6 3 9 1 |(5)47 | 8 | 6
+-------------+ +------+ +-------------+------+------+
| 6 1 9 3 | 7 | 5 2 8 | 4 | 5
+-------------+-------------+ +------+ +------+ |
| 3 9 | 4 8 5 2 | 6 | 1(7) 1(7) | 4
+------+ +-------------+-------------+ +------+ |
| 2 | 8 157 457 | 14 3 4(7) 9 | 6 | 3
| +-------------+ +-------------+------+ | |
| 8 457 157 | 2 6 47 | 9 | 14(7)| 3 | 2
| +-------------+ | +------+ |
| 47 6 3 147 9 | 147 | 8 2(5) 2(5) | 1
+----------------------------------+------+--------------------+
a b c d e f g h i
[9 placements, 1 lc elimination, ste]
I propose the following Jigsaw puzzle that can be solved in two steps.
(not a lot of givens, like the last one!)
(generated with 1to9only release of SudokuExplainer)
After basics, one should reach the following configuration
+--------------------------+--------+--------------------------------------------+
| 3459 35789 35789 | 4578 | 2358 1 3458 23578 6 | 99999
| | +-----------------+ +--------+ |
| 245 1 578 | 3 245689 256789 | 458 | 25678 | 789 | 8
| +-----------------+-----------------+ +--------+ | |
| 2345 | 345789 6 4578 34589 | 25789 1589 12578 | 3789 | 7
| +--------+ +-----------------+-----------------+ | |
| 345 6 | 34579 | 158 13589 3589 2 | 57 | 379 | 6
+-----------------+ +--------+ +-----------------+--------+--------+
| 1 3589 2 58 | 7 | 35689 3589 3568 | 4 | 5
+-----------------+-----------------+ +--------+ +--------+ |
| 8 2 | 359 56 3569 4 | 1359 | 37 137 | 4
+--------+ +-----------------+-----------------+ +--------+ |
| 6 | 45 45 9 | 1238 238 7 1238 | 138 | 3
| +-----------------+ +-----------------+--------+ | |
| 359 3589 3589 | 167 136 367 | 368 | 4 | 2 | 2
| +-----------------+ | +--------+ |
| 7 348 1 2 348 | 36 | 368 9 5 | 1
+--------------------------------------------+--------+--------------------------+
a b c d e f g h i
Update (Jun 15, 2025)
Look at the pattern of 7. There is a powerful fish giving 15 placements and lots of basics.
Next, there is a nice wing elimination that solves the puzzle with singles to the end.
Final Update (Jun 16, 2025)
+--------------------------+--------+--------------------------------------------+
| 3459 35(7)89 35789 | 4578 | 2358 1 3458 2358-7 6 | 99999
| | +-----------------+ +--------+ |
| 245 1 578 | 3 245689 256789 | 458 | 25678 | 789 | 8
| +-----------------+-----------------+ +--------+ | |
| 2345 | 345(7)89 6 4578 34589 | 25789 1589 12578 | 3789 | 7
| +--------+ +-----------------+-----------------+ | |
| 345 6 | 345(7)9| 158 13589 3589 2 | 5(7) | 3(7)9 | 6
+-----------------+ +--------+ +-----------------+--------+--------+
| 1 3589 2 58 | 7 | 35689 3589 3568 | 4 | 5
+-----------------+-----------------+ +--------+ +--------+ |
| 8 2 | 359 56 3569 4 | 1359 | 37 137 | 4
+--------+ +-----------------+-----------------+ +--------+ |
| 6 | 45 45 9 | 1238 238 7 1238 | 138 | 3
| +-----------------+ +-----------------+--------+ | |
| 359 3589 3589 | 167 136 367 | 368 | 4 | 2 | 2
| +-----------------+ | +--------+ |
| 7 348 1 2 348 | 36 | 368 9 5 | 1
+--------------------------------------------+--------+--------------------------+
a b c d e f g h i
Step 1 (above) => -7 h9 [15 placements with long basics]
---
For step 2, find a Y-wing that solves the puzze.
I found a nice Jigsaw puzzle that can be solved in three steps.
(generated with 1to9only release of SudokuExplainer)
After basics, one should reach the following configuration
+--------------------+------+----------------------------------+
| 6 1457 157 | 8 | 57 9 2 3 14 | 9
| | +-------------+ +------+ |
| 157 1457 8 | 6 2 3 | 57 | 9 | 14 | 8
| +-------------+-------------+ +------+ | |
| 9 | 6 2 157 3 | 145 1457 1457 | 8 | 7
| +------+ +-------------+-------------+ | |
| 2 3 | 4 | 57 157 8 9 | 157 | 6 | 6
+-------------+ +------+ +-------------+------+------+
| 8 157 1579 1579 | 6 | 145 3 1457 | 2 | 5
+------+------+-------------+ +------+ +------+ |
| 15 | 8 | 3 4 157 2 | 157 | 6 9 | 4
| | +-------------+-------------+ +------+ |
| 4 | 2 15 3 | 9 15 6 8 | 7 | 3
| +------+ +-------------+------+ | |
| 157 157 | 159 159 4 6 | 8 | 2 | 3 | 2
| +--------------------+ | +------+ |
| 3 9 6 2 8 | 7 | 14 14 5 | 1
+----------------------------------+------+--------------------+
a b c d e f g h i
Update (Jun 18, 2025)
One way in 3 steps starts with the UR available in the grid after basics.
(it eliminates (1)b8, (1)b9).
For the second step, we need to go fishing !
Update (Jun 19, 2025)
After getting the fish, we obtain the following configuration
+-----------------+-----+-----------------------------+
| 6 45 15 | 8 | 7 9 2 3 14 | 9
| | +-----------+ +-----+ |
| 17 47 8 | 6 2 3 | 5 | 9 | 14 | 8
| +-----------+-----------+ +-----+ | |
| 9 | 6 2 15 3 | 145 14 7 | 8 | 7
| +-----+ +-----------+-----------+ | |
| 2 3 | 4 | 7 15 8 9 | 15 | 6 | 6
+-----------+ +-----+ +-----------+-----+-----+
| 8 15 7 9 | 6 | 145 3 145 | 2 | 5
+-----+-----+-----------+ +-----+ +-----+ |
| 15 | 8 | 3 4 15 2 | 7 | 6 9 | 4
| | +-----------+-----------+ +-----+ |
| 4 | 2 15 3 | 9 15 6 8 | 7 | 3
| +-----+ +-----------+-----+ | |
| 157 17 | 9 15 4 6 | 8 | 2 | 3 | 2
| +-----------------+ | +-----+ |
| 3 9 6 2 8 | 7 | 14 14 5 | 1
+-----------------------------+-----+-----------------+
a b c d e f g h i
How to finish the puzzle ?
Update (Jun 20, 2025)
Two nice ways to finish:
. Remote Pair (15) to eliminate (1) and (5) from h5
. Extended Unique Rectangle to eliminate (5)f3.
I propose the following pleasant Sudoku-X puzzle, solvable in two steps.
(generated with 1to9only release of SudokuExplainer)
After long basics, one should reach the following configuration
+--------------------+------+----------------------------------+
| 129 3 6 | 4 | 5 1279 8 1279 179 | 9
| | +-------------+ +------+ |
| 1249 7 5 | 89 289 129 | 24 | 3 | 6 | 8
| +-------------+-------------+ +------+ | |
| 1249 | 8 14 6 3 | 1279 5 1279 | 149 | 7
| +------+ +-------------+-------------+ | |
| 8 14 | 124 | 5 249 249 7 | 6 | 3 | 6
+-------------+ +------+ +-------------+------+------+
| 5 24 9 7 | 6 | 3 124 8 | 124 | 5
+------+------+-------------+ +------+ +------+ |
| 7 | 6 | 3 1 24 8 | 249 | 49 5 | 4
| | +-------------+-------------+ +------+ |
| 14 | 249 248 3 | 7 6 149 5 | 189 | 3
| +------+ +-------------+------+ | |
| 3 5 | 7 89 1 49 | 6 | 24 | 289 | 2
| +--------------------+ | +------+ |
| 6 149 48 2 489 | 5 | 3 147 17 | 1
+----------------------------------+------+--------------------+
a b c d e f g h i
Update (Sept 15, 2025)
My first step is based on a W-wing, but gets a bit more out of it.
Update (Sept 16, 2025)
The move already described eliminates (4)b6 and (4)g5, giving 5 placements and basics.
Now a very simple fish solves the puzzle with singles afterwards.