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Puzzle NR 09/11/17 (A)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Nov 17, 2009 4:54 pm    Post subject: Puzzle NR 09/11/17 (A) Reply with quote

Code:
 +-----------------------+
 | . 3 . | 2 . . | . . . |
 | 5 . 4 | 6 . . | . 3 7 |
 | . 7 . | . 5 3 | . . . |
 |-------+-------+-------|
 | 4 1 . | . 6 . | . 5 2 |
 | . . 2 | 1 3 . | . . . |
 | . . 6 | . . . | . . 1 |
 |-------+-------+-------|
 | . . . | . . . | 7 . . |
 | . 6 . | 7 . . | . 9 3 |
 | . 4 . | 3 . 9 | . 1 8 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Wed Nov 18, 2009 6:13 am    Post subject: Reply with quote

I had difficulty; a six-stepper.

ER, Hidden UR, W-Wing, XY-Wing, XY-Wing with pincer transport and a Kite.
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Wed Nov 18, 2009 9:11 am    Post subject: Reply with quote

I too had difficulty:
skyscraper 2
w-wing 74
xy-wing 895
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Wed Nov 18, 2009 3:58 pm    Post subject: Reply with quote

I was in the same situation; moves were hard to spot and some seem not to be useful.

My three moves were a

skyscraper 2 in r7c28,
a xy-wing 4-78 with the vertex extended into a chain: (7=4)r1c6 - (4=8)r3c4 - (8=5)r7c4 - (5=4)r6c4 - (4=7)r6c5; r1c5, r5c6<>7
xy-wing 5-89 with vertex 59 in r6c2, pincer 89 in r5c1 and pincer 58 is a pseudocell in r36c4; r3c1<>8. Then transport 8 in r5c1: (8)r5c1 - (8)r5c2 = (8)r7c2; r7c4<>8 to complete the puzzle.

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Nov 18, 2009 5:06 pm    Post subject: Reply with quote

It's interesting how some puzzles end up being more difficult than my solver would indicate.

Code:
   c3b1  Locked Candidate 2              <> 9    r13c1,r2c2

 c28r7   Skyscraper                      <> 2    r2c7,r3c1   -or-
 r28c7   Skyscraper                      <> 2    r3c1,r7c2

   c7    Naked  Triple                   <> 489  r138c7

 r7  b9  Locked Candidate 1              <> 4    r7c45

   c7b6  Locked Candidate 2              <> 4    r5c89,r6c8

         XY-Wing  r7c4/r3c4+r7c9         <> 4    r3c9   extraneous
         XY-Wing  r7c4/r3c4+r8c6         <> 4    r1c6

         XY-Wing  r7c2/r6c2+r7c4         <> 5    r6c4
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Wed Nov 18, 2009 6:40 pm    Post subject: Reply with quote

daj95376 wrote:
It's interesting how some puzzles end up being more difficult than my solver would indicate.

Code:
   c3b1  Locked Candidate 2              <> 9    r13c1,r2c2

 c28r7   Skyscraper                      <> 2    r2c7,r3c1   -or-
 r28c7   Skyscraper                      <> 2    r3c1,r7c2

   c7    Naked  Triple                   <> 489  r138c7

 r7  b9  Locked Candidate 1              <> 4    r7c45

   c7b6  Locked Candidate 2              <> 4    r5c89,r6c8

         XY-Wing  r7c4/r3c4+r7c9         <> 4    r3c9   extraneous
         XY-Wing  r7c4/r3c4+r8c6         <> 4    r1c6

         XY-Wing  r7c2/r6c2+r7c4         <> 5    r6c4


Danny, I agree with your comment. I frequently note that others found a much easier/simpler solution than I did, but it is particularly interesting when several people all agree that a puzzle was difficult.

In this case, I now realize that the basic xy-wings your solver found were available at the stage when I found a more involved xy-wing; I simply found the longer solution before getting around to the simple one.

This is all part of the enjoyment of Sudoku

Ted
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