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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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 Posted: Fri Jan 08, 2010 9:18 am Post subject: Diabolical |
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The following puzzle appeared in the Sydney Morning Herald (Australia) on 7 January. I think it is syndicated from the Telegraph (UK). It was rated "diabolical" (the highest of four levels). Usually I am able to solve diabolicals with a wing or two but in this case, my limited bag of tools proved to be insufficient.
When I loaded it into the DailySudoku grid, the program graded it as "Too Hard".
I'd be interested to see if the experts who frequent this place can solve it and explain the techniques used.
| Code: |
+-------+-------+-------+
| . . . | 6 8 . | . . 7 |
| 5 . . | 9 . 1 | . 3 . |
| . . 7 | . . 4 | 6 . . |
+-------+-------+-------+
| 4 2 . | . . . | . . 9 |
| . 5 . | . . . | . 1 . |
| 8 . . | . . . | . . 5 |
+-------+-------+-------+
| . . 2 | 5 . . | 4 . . |
| . 4 . | 1 . 2 | . . 8 |
| 3 . . | . . 9 | . . . |
+-------+-------+-------+
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Cheers,
Ron |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Fri Jan 08, 2010 9:48 am Post subject: |
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Ron,
I never use draw/play, I do it by hand (pen and paper).
After basics
| Code: |
+--------------------------+--------------------------+--------------------------+
| 2 13 134 | 6 8 35 | 59 459 7 |
| 5 68 468 | 9 7 1 | 28 3 24 |
| 9 38 7 | 23 25 4 | 6 58 1 |
+--------------------------+--------------------------+--------------------------+
| 4 2 136 | 378 15 35678 | 378 68 9 |
| 67 5 369 | 23478 29 3678 | 2378 1 246 |
| 8 13679 1369 | 2347 129 367 | 237 246 5 |
+--------------------------+--------------------------+--------------------------+
| 1 789 2 | 5 6 78 | 4 79 3 |
| 67 4 569 | 1 3 2 | 59 5679 8 |
| 3 678 568 | 78 4 9 | 1 2567 26 |
+--------------------------+--------------------------+--------------------------+
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there is a skyscraper (6) cols 1 and 9 that does it.
----
edit 1101 GMT+1: I ran the puzzle through play/draw and indeed it says "too hard".
At the point where dailysudoku's solver surrenders,
| Code: |
+---------------+-----------------+---------------+
| 2 13 134 | 6 8 35 | 59 459 7 |
| 5 68 468 | 9 7 1 | 28 3 24 |
| 9 38 7 | 23 25 4 | 6 258 1 |
+---------------+-----------------+---------------+
| 4 2 136 | 378 15 35678 | 378 678 9 |
| 67 5 369 | 23478 29 3678 | 2378 1 246 |
| 8 13679 1369 | 2347 129 367 | 237 2467 5 |
+---------------+-----------------+---------------+
| 1 789 2 | 5 6 78 | 4 79 3 |
| 67 4 569 | 1 3 2 | 579 5679 8 |
| 3 678 568 | 78 4 9 | 1 2567 26 |
+---------------+-----------------+---------------+
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there is a box/line (2) row 2 box 3 (and a hidden pair/naked quad in col 7).
hm.
weird. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Jan 08, 2010 3:00 pm Post subject: |
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Indeed this is fascinating/confusing.
Simple Sudoku accepts the puzzle correctly without complaint and locates the skyscraper in r4c19, which completes the puzzle. No problems!
However, Sudoku Susser has a fatal problem loading the puzzle. It places a couple of the original digits in different cells of the grid, and then indicates the puzzle has no solution.
Danny, it would be interesting to know how your solver handles this puzzle.
Ted |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Jan 08, 2010 3:13 pm Post subject: |
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| tlanglet wrote: |
However, Sudoku Susser has a fatal problem loading the puzzle. It places a couple of the original digits in different cells of the grid, and then indicates the puzzle has no solution.
Ted |
I loaded the puzzle into Sudoku Susser with no problem. Of course, it does not find skyscrapers.
Keith |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Jan 08, 2010 5:48 pm Post subject: |
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| tlanglet wrote: | Danny, it would be interesting to know how your solver handles this puzzle.
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Hello Ted,
My solver loads and solves this puzzle w/o any problems.
Regards, Danny |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Jan 08, 2010 6:33 pm Post subject: |
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| keith wrote: |
I loaded the puzzle into Sudoku Susser with no problem. Of course, it does not find skyscrapers.
Keith |
Keith,
I have copied/pasted this puzzle into Sudoku Susser version 2.5.8 many times with the same failed result.
| Code: | +-------+-------+-------+
| . . . | 6 8 . | . 7 . |
| 5 . . | . 9 1 | . 3 . |
| . . 7 | . . 4 | 6 . . |
+-------+-------+-------+
| 4 2 . | . . . | . . 9 |
| . 5 . | . . . | . 1 . |
| 8 . . | . . . | . . 5 |
+-------+-------+-------+
| . . 2 | . 5 . | 4 . . |
| . 4 . | . 1 2 | . . 8 |
| 3 . . | . . 9 | . . . |
+-------+-------+-------+ |
The differences I noticed were:
the 7 in r1c9 is moved to r1c8,
the 9 in r2c4 is moved to r2c5,
the 5 in r7c4 is moved to r7c5,
the 1 in r8c4 is moved to r8c5.
What version are you using?
Can you think of any other possible explanations?
Also, Simple Sudoku also does not specifically identify skyscrapers, but it uses coloring to point out the deletions of one pincer of a skyscraper.
Ted |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Jan 08, 2010 6:47 pm Post subject: |
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Ted,
I have the same version on a PC running Win XP. Does this work?
| Code: | Puzzle: New Puzzle #79
+-------+-------+-------+
| . . . | 6 8 . | . . 7 |
| 5 . . | 9 . 1 | . 3 . |
| . . 7 | . . 4 | 6 . . |
+-------+-------+-------+
| 4 2 . | . . . | . . 9 |
| . 5 . | . . . | . 1 . |
| 8 . . | . . . | . . 5 |
+-------+-------+-------+
| . . 2 | 5 . . | 4 . . |
| . 4 . | 1 . 2 | . . 8 |
| 3 . . | . . 9 | . . . |
+-------+-------+-------+ |
I assume you are highlighting the text, then edit ... copy (ctrl+c) and then edit ... paste (ctrl+v) in the Susser window.
Susser does have a bug in that it does not recognize a puzzle if an entire row or column has no initial clues.
Keith |
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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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| Posted: Sat Jan 09, 2010 2:27 am Post subject: |
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Many thanks everyone. Seems I'm just going to have to learn about skyscrapers.
Cheers |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Jan 09, 2010 3:40 am Post subject: |
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| kragzy wrote: | Many thanks everyone. Seems I'm just going to have to learn about skyscrapers.
Cheers |
kragzy,
Havard's "Strong Links for Beginners" led me to a quantum leap in solving puzzles.
http://forum.enjoysudoku.com/strong-links-for-beginners-t3326.html
In my book, Turbot Fish and Kites are the same thing as Skyscrapers. Empty Rectangles are almost the same thing.
Keith
Last edited by keith on Wed Feb 16, 2011 8:28 am; edited 1 time in total |
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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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| Posted: Sun Jan 10, 2010 8:45 am Post subject: |
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| Thanks Keith. |
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