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Ninja Sudoku
http://www.rcbroughton.co.uk/sudoku/forum/viewtopic.php?f=4&t=847
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Author:  enxio27 [ Wed Dec 01, 2010 6:39 pm ]
Post subject:  Re: Ninja Sudoku

I finished the Kunoichi, but unless I messed something up, the upper left and lower right grids have more than one solution:

5, 8 in Grid #1, r4c17, r5c47, r6c14
2, 5 in Grid #5, r4c69, r5c36, r6c39

Author:  simon_blow_snow [ Wed Dec 01, 2010 9:44 pm ]
Post subject:  Re: Ninja Sudoku

You are right enxio27. For some reasons I forgot to take out the short diagonals when checking for uniqueness. :oops:

If you assume those short diagonals are there (as in the Ninja Sudoku) the solution is unique.

Should I create another puzzle to make it up for you?

Author:  enxio27 [ Thu Dec 02, 2010 3:52 am ]
Post subject:  Re: Ninja Sudoku

simon_blow_snow wrote:
You are right enxio27. For some reasons I forgot to take out the short diagonals when checking for uniqueness. :oops:

If you assume those short diagonals are there (as in the Ninja Sudoku) the solution is unique.

No worries! At least I know it wasn't because I messed up the puzzle somehow.

Quote:
Should I create another puzzle to make it up for you?

Ooh, that would be fun! :bouncy: :dance:

Author:  simon_blow_snow [ Thu Dec 02, 2010 7:01 am ]
Post subject:  Re: Ninja Sudoku

Here is a make-up puzzle to enxio27 for my earlier blunder :oops: (also for her earlier comment that #1 was "a little easier than expected" :twisted:):

Kunoichi Sudoku #2

Image

text representation:
Code:
#|. 1 . 2 . 3 . 4 .|#_#_#_#_#_#_#_#_#
#|2 . . . . . 5 . 6|. 7 . 8 . 1 . 9 .
#|. 4 . . . . . . .|8 . . . . . 2 . 3
#|8 . . . . . . . 1|. 9 . . . . . . .
#|. . . . ._._._._.|6_._._. . . . . 7
#|3 . . .|. . . . .|. . . .|. . . . .
#|. . . .|. . . . .|. . . .|. . . . 9
#|7 . 2 .|. . . . .|. . . .|. . . 6 .
#|._8_._1|._._._. .|. . . .|. . . . 2
. 9 . 6 .|. . . .|.|._._._.|._2_._1 .
6 . . . .|. . . .|. . . . .|9 . 8 .|#
. 2 . . .|. . . .|. . . . .|. 6 . 4|#
1 . . . .|. . . .|. . . . .|. . . .|#
. . . . .|._._._.|._._._._.|. . . 5|#
4 . . . . . . . 2|. . . . . . . . .|#
. . . . . . . 1 .|9 . . . . . . . 8|#
5 . 6 . . . . . 8|. . . . . . . 7 .|#
._1_._9_._8_._4_.|2 . 3 . . . . . 6|#
# # # # # # # # #|._7_._5_._6_._9_.|#

codes for the 5 grids (top-left, top-right, central, bottom-left, bottom-right:
Code:
.1.2.3.4.2.....5.6.4.......8.......1.........3.................7.2.......8.1.....
.7.8.1.9.8.....2.3.9.......6.......7.................9.......6.........2.....2.1.
.................................................................................
.9.6.....6.........2.......1.................4.......2.......1.5.6.....8.1.9.8.4.
.....9.8.......6.4.................5.........9.......8.......7.2.3.....6.7.5.6.9.

initial pencilmark grids:
Code:
+----------------------------------+----------------------------------+----------------------------------+
| 596        1          75986      | 2          75986      3          | 798        4          798        |
| 2          793        7983       | 7984       79814      79814      | 5          79813      6          |
| 596        4          759863     | 75986      759861     759861     | 792813     792813     79283      |
+----------------------------------+----------------------------------+----------------------------------+
| 8          75926      75964      | 759634     7592634    759264     | 792634     759263     1          |
| 59614      75926      759614     | 7598634    759286134  75928614   | 7928634    7592863    7592834    |
| 3          75926      759614     | 759864     75928614   75928614   | 792864     759286     759284     |
+----------------------------------+----------------------------------+----------------------------------+
| 59614      5963       596134     | 7598634    75928634   7592864    | 79286134   75928613   7592834    |
| 7          5963       2          | 598634     598634     59864      | 986134     598613     59834      |
| 5964       8          59634      | 1          7592634    759264     | 792634     759263     759234     |
+----------------------------------+----------------------------------+----------------------------------+

+----------------------------------+----------------------------------+----------------------------------+
| 5234       7          52634      | 8          52634      1          | 564        9          564        |
| 8          5614       5614       | 75964      75964      75964      | 2          754        3          |
| 52134      9          526134     | 752634     752634     75634      | 758614     7584       58614      |
+----------------------------------+----------------------------------+----------------------------------+
| 6          528134     5928134    | 592134     5928134    59834      | 58134      52834      7          |
| 7592134    528134     75928134   | 75926134   759286134  7598634    | 586134     52834      58614      |
| 752134     528134     7528134    | 7526134    75286134   758634     | 586134     52834      9          |
+----------------------------------+----------------------------------+----------------------------------+
| 7592134    528134     75928134   | 759134     7598134    759834     | 759834     6          584        |
| 759134     586134     75986134   | 7596134    75986134   7598634    | 759834     75834      2          |
| 75934      58634      7598634    | 759634     7598634    2          | 759834     1          584        |
+----------------------------------+----------------------------------+----------------------------------+

+----------------------------------+----------------------------------+----------------------------------+
| 75928614   75928614   792864     | 759286     759284     7592134    | 528134     75928134   75926134   |
| 75928634   7592864    79286134   | 75928613   7592834    752134     | 528134     7528134    7526134    |
| 598634     59864      986134     | 598613     59834      7592134    | 528134     75928134   759134     |
+----------------------------------+----------------------------------+----------------------------------+
| 7592634    759264     792634     | 759263     759234     759134     | 586134     75986134   7596134    |
| 752134     7528134    75283      | 75134      759286134  75934      | 58634      7598634    759634     |
| 7592134    75928134   759283     | 759134     756134     526134     | 752614     726134     7526134    |
+----------------------------------+----------------------------------+----------------------------------+
| 759134     75986134   759863     | 7596134    75813      592813     | 759281     72813      752813     |
| 7592634    7598634    759863     | 759634     7586134    59286134   | 75928614   7286134    75286134   |
| 75926134   75986134   759863     | 7596134    786134     286134     | 728614     79286134   79286134   |
+----------------------------------+----------------------------------+----------------------------------+

+----------------------------------+----------------------------------+----------------------------------+
| 783        9          758134     | 6          7528134    752134     | 7528134    75283      75134      |
| 6          75834      758134     | 7528134    75928134   7592134    | 75928134   759283     759134     |
| 783        2          758134     | 758134     7598134    759134     | 75986134   759863     7596134    |
+----------------------------------+----------------------------------+----------------------------------+
| 1          75863      759283     | 752834     75928634   7592634    | 7598634    759863     759634     |
| 79283      75863      759283     | 7528134    759286134  75926134   | 75986134   759863     7596134    |
| 4          75863      75983      | 75813      7598613    759613     | 7598613    759863     2          |
+----------------------------------+----------------------------------+----------------------------------+
| 79283      7834       792834     | 75234      752634     752634     | 759263     1          75963      |
| 5          734        6          | 72134      72134      72134      | 7923       7923       8          |
| 723        1          723        | 9          75263      8          | 75263      4          7563       |
+----------------------------------+----------------------------------+----------------------------------+

+----------------------------------+----------------------------------+----------------------------------+
| 756134     526134     752614     | 726134     7526134    9          | 75213      8          7213       |
| 75813      592813     759281     | 72813      752813     752813     | 6          5213       4          |
| 7586134    59286134   75928614   | 7286134    75286134   7528134    | 759213     5213       79213      |
+----------------------------------+----------------------------------+----------------------------------+
| 786134     286134     728614     | 79286134   79286134   728134     | 792134     26134      5          |
| 7586134    5286134    7528614    | 79286134   759286134  7528134    | 792134     26134      79213      |
| 9          526134     752614     | 726134     7526134    752134     | 72134      26134      8          |
+----------------------------------+----------------------------------+----------------------------------+
| 58614      598614     598614     | 928134     928134     28134      | 528134     7          213        |
| 2          59814      3          | 79814      79814      7814       | 5814       514        6          |
| 814        7          814        | 5          28134      6          | 28134      9          213        |
+----------------------------------+----------------------------------+----------------------------------+

text solution:
Code:
#|5 1 6 2 7 3 9 4 8|#_#_#_#_#_#_#_#_#
#|2 7 3 9 4 8 5 1 6|2 7 3 8 4 1 5 9 6
#|9 4 8 5 1 6 2 7 3|8 4 1 5 9 6 2 7 3
#|8 5 7 6 2 4 3 9 1|5 9 6 2 7 3 8 4 1
#|6 2 4 3 9_1_8_5_7|6_2_4_3 8 9 1 5 7
#|3 9 1 8|5 7 6 2 4|3 8 9 1|5 7 6 2 4
#|1 6 5 7|3 2 4 8 9|1 5 7 6|2 4 3 8 9
#|7 3 2 4|8 9 1 6 5|7 3 2 4|1 8 9 6 5
#|4_8_9_1|6_5_7_3 2|4 1 8 9|6 5 7 3 2
8 9 7 6 5|4 3 2 1|8|9_6_5_7|3_2_4_1 8
6 5 4 3 2|1 8 9 7|6 5 4 3 2|9 1 8 7|#
3 2 1 8 9|7 6 5 4|3 2 9 1 8|7 6 5 4|#
1 8 5 7 6|2 4 3 9|1 8 7 6 5|4 3 2 9|#
7 6 2 4 3|9_1_8_5|7_6_2_4_3|8 9 1 5|#
4 3 9 1 8 5 7 6 2|4 3 8 9 1 5 7 6 2|#
9 7 8 5 4 6 2 1 3|9 1 5 7 6 2 4 3 8|#
5 4 6 2 1 3 9 7 8|5 4 6 2 9 3 8 7 1|#
2_1_3_9_7_8_5_4_6|2 9 3 8 7 1 5 4 6|#
# # # # # # # # #|8_7_1_5_4_6_2_9_3|#

(Someone please tell me my solution is the only unique one this time.)

Author:  enxio27 [ Thu Dec 02, 2010 4:51 pm ]
Post subject:  Re: Ninja Sudoku

simon_blow_snow wrote:
Here is a make-up puzzle to enxio27 for my earlier blunder :oops: (also for her earlier comment that #1 was "a little easier than expected" :twisted:):

Uh-oh! I think I'm in trouble now! :pallid:

I'll give it a try as soon as I finish the Clueless Special I'm working on (which is also turning out to be "easier than expected").

Author:  enxio27 [ Tue Dec 21, 2010 3:30 am ]
Post subject:  Re: Ninja Sudoku

Finished Kunoichi #2! A very nice puzzle, challenging but not frustrating. Solving time was also just right, long enough to be interesting, but not interminable. Thank you very much for posting it!

Author:  simon_blow_snow [ Tue Dec 21, 2010 5:37 pm ]
Post subject:  Re: Ninja Sudoku

Glad you like it, enxio27! :santa:

In fact Kunoichi #1 & #2 are both from the same solution grid, just the symbols/values are scrambled. In a way their positions of the initial givens are complements of each other.

If I knew #2 would be human solvable (and hopefully "enjoyable") than there was not much point of having the #1, which was quite a disappoinment and embarassment. :oops:

Author:  enxio27 [ Tue Aug 06, 2013 1:13 am ]
Post subject:  Re: Ninja Sudoku

simon_blow_snow, are you still around? Got to thinking wistfully today about the Kunoichi puzzles you made for me, and wishing for another one. :sun:

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