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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Fri Mar 19, 2010 2:13 am Post subject: Free Press Mar 18, 2010 (Thursday) |
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A very good very hard. (I enjoyed the basics.)
| Code: | Puzzle: DS031810
+-------+-------+-------+
| . . 9 | . 7 . | . . . |
| . 2 . | 5 . 1 | . . . |
| 5 . . | . . 9 | . . 8 |
+-------+-------+-------+
| 3 1 . | . . . | . 8 . |
| . . . | . 8 . | 9 . . |
| . 5 . | . . . | . 3 6 |
+-------+-------+-------+
| 1 . . | . . . | . . 2 |
| . . . | 2 . 3 | . 7 . |
| . . 3 | . 1 . | 6 . . |
+-------+-------+-------+ |
Keith
Last edited by keith on Fri Mar 19, 2010 4:35 pm; edited 1 time in total |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Mar 19, 2010 4:44 am Post subject: |
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Definitely lots of basics, after which I used three steps.
| Quote: | Type 4 UR (78)
Type 1 UR (56)
BUG+1 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Mar 19, 2010 4:51 am Post subject: |
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Yes, I also found the basics interesting for this puzzle.
My three steps to solve the puzzle were:
| Quote: | UR 78 in r79c24. Looking at the outside constraints, no 7 exist in r79 but r79c6=8. Thus a 8 in required in r79c6 which deletes the 8 in r1c6,
Type 1 UR 56 in r78c35 sets r7c5=9,
BUG+1 forces r3c5=6.
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Ted |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Fri Mar 19, 2010 6:50 am Post subject: |
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Very good puzzle. I like it when the basics provide some challenge.
I found an xyz-wing 36-236-26 box 2 / row 3 that did it. Cannot remember if I used any other advanced moves but I don't think so. |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Fri Mar 19, 2010 8:09 am Post subject: |
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What is it? | Code: |
*--------------------------------------------------------------------*
| 6 34 9 | 48 7 248 | 1 25 35 |
| 8 2 7 | 5 *36 1 | 4 69 39 |
| 5 *34 1 |*46 26-3 9 | 7 26 8 |
|----------------------+----------------------+----------------------|
| 3 1 4 | 69 269 26 | 5 8 7 |
| 7 6 2 | 3 8 5 | 9 1 4 |
| 9 5 8 | 1 4 7 | 2 3 6 |
|----------------------+----------------------+----------------------|
| 1 78 56 | 46789 569 468 | 3 49 2 |
| 4 9 56 | 2 56 3 | 8 7 1 |
| 2 78 3 | 4789 1 48 | 6 459 59 |
*--------------------------------------------------------------------*
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is it an xy-346?
It removes the 3 from r3c5 to solve the puzzle. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Mar 19, 2010 1:26 pm Post subject: |
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| nataraj wrote: | Very good puzzle. I like it when the basics provide some challenge.
I found an xyz-wing 36-236-26 box 2 / row 3 that did it. Cannot remember if I used any other advanced moves but I don't think so. |
Nataraj,
I noticed the URs immediately after basics and never looked at any other conditions. Your xyz-wing was a good find.
The xyz-wing could also be viewed as a finned xy-wing as I noted in a post here in the Solving Techniques thread of this forum. The finned xy-wing provided additional deletions (which were not needed in this case to complete the puzzle).
Ted |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Fri Mar 19, 2010 1:26 pm Post subject: |
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Same as Marty two URs and a Bug+1. Probably the easiest to spot.
It's not really relevant but there were so many initial <4>s (I counted 48). I wonder what the maximum number of a single digit could be - probably 72. And why am I worried? |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Mar 19, 2010 2:35 pm Post subject: |
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I used that same XY-wing as Ted.
| cgordon wrote: | It's not really relevant but there were so many initial <4>s (I counted 4 . I wonder what the maximum number of a single digit could be - probably 72. And why am I worried? |
There are 81 cells, and the minimum number of clues is 17. Note that one digit may be missing in the initial clues, so I suppose the answer is 81 - 17 = 64.
Keith |
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