The New Sudoku Players' Forum

[AnotherLife]

I think this puzzle will be my last one before a long break, and one day I will return to the forum.
This sudoku seems very hard but maybe someone will find a nice solution to it.

Code: Select all

.51.3...9.8.1......6..2.3...48.53.71.....1.9...2.4.....2...5.435....9..6...4....7

Code: Select all

.-------------------.------------------.-------------------.
| 247    5     1    | 678   3     4678 | 24678  268   9    |
| 23479  8     3479 | 1     679   467  | 24567  256   245  |
| 479    6     479  | 5789  2     478  | 3      158   458  |
:-------------------+------------------+-------------------:
| 69     4     8    | 269   5     3    | 26     7     1    |
| 367    37    3567 | 2678  678   1    | 24568  9     2458 |
| 13679  1379  2    | 6789  4     678  | 568    3568  58   |
:-------------------+------------------+-------------------:
| 16789  2     679  | 678   1678  5    | 189    4     3    |
| 5      137   347  | 2378  178   9    | 128    128   6    |
| 13689  139   369  | 4     168   268  | 12589  1258  7    |
'-------------------'------------------'-------------------'


[eleven]

Nice one, thanks.

[AnotherLife]

Hello, eleven,
I will be waiting for someone to write a solution before I give a hint.

Regards,
Bogdan

[Cenoman]

Nice trap, Bogdan !
Original puzzle:

Code: Select all

 +---+---+---+
 |.51|.3.|..9|
 |.8.|1..|...|
 |.6.|.2.|3..|
 +---+---+---+
 |.48|.53|.71|
 |...|..1|.9.|
 |..2|.4.|...|
 +---+---+---+
 |.2.|..5|.43|
 |5..|..9|..6|
 |...|4..|..7|
 +---+---+---+

By the isomorphism: swap rows[45], swap columns[45], swap circularly rows [789->978], swap circularly columns [789->978] the original puzzle is morphed to the following:

Code: Select all

 +---+---+---+
 |.51|3..|.9.|
 |.8.|.1.|...|
 |.6.|2..|..3|
 +---+---+---+
 |...|..1|9..|
 |.48|5.3|71.|
 |..2|4..|...|
 +---+---+---+
 |5..|..9|.6.|
 |...|.4.|.7.|
 |.2.|..5|43.|
 +---+---+---+

... having a central symmetry with the digit permutation [14][29][35][66][78] =>+6r5c5

The cell in the original puzzle, corresponding to r5c5, is r4c4, so +6r4c4, which leads to the following resolution state:

Code: Select all

 +------------------+---------------------+------------------+
 |  2     5    1    |  78   3      4678   |  478   68   9    |
 |  347   8    37   |  1    9      467    |  457   56   2    |
 |  47*   6    9    |  5    2      478*   |  3     1    48   |
 +------------------+---------------------+------------------+
 |  9     4    8    |  6    5      3      |  2     7    1    |
 |  6-7   3    5    |  2    78     1      |  468   9    48   |
 |  167*  17*  2    |  9    4      78*    |  68    3    5    |
 +------------------+---------------------+------------------+
 |  178   2    67   |  78   1678   5      |  9     4    3    |
 |  5     17   4    |  3    178    9      |  18    2    6    |
 |  138   9    36   |  4    168    2      |  158   58   7    |
 +------------------+---------------------+------------------+

Finned X-Wing: (7)r3c1 = r3c6 - r6c6 = r6c12 => -7 r5c1; ste

Aknowledgements to yzfwsf's solver !

[AnotherLife]

Hi, Cenoman,
I knew you would make it! Congratulations! How did yzfwsf's solver help you to solve the puzzle? I have the version 2.0.0.614, and it is useless in this case as well as HoDoKu.

[eleven]

Aknowledgements to yzfwsf's solver !

It was easy to find the symmetry here. Obviously boxes 19,28,37 and 46 have the same box pattern (no others would match).

[mith]

Hi, Cenoman,
I knew you would make it! Congratulations! How did yzfwsf's solver help you to solve the puzzle? I have the version 2.0.0.614, and it is useless in this case as well as HoDoKu.

The current version (2.0.0.620) supports symmetry.

[AnotherLife]

The current version (2.0.0.620) supports symmetry.

Thanks for the valuable information.

I will be absent for a long period, so it is time to say goodbye to everybody. Thanks for your good and professional company!

Best regards,
Bogdan