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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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 Posted: Sun Mar 30, 2008 7:57 pm Post subject: Don't . . . |
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. . . do this unless you like XY-chains and/or fancy your chances of finding some clever alternative. M4061727 (71)
| Code: |
+-------+-------+-------+
| 6 . 7 | 4 . . | . 8 . |
| 3 . 5 | . . 2 | . . . |
| . 1 . | . 8 . | . . . |
+-------+-------+-------+
| . 5 . | . 4 . | . 3 . |
| . . . | 7 . 6 | . . . |
| 7 . 2 | . 5 . | 9 . 4 |
+-------+-------+-------+
| . . . | . 1 . | . 7 . |
| 5 . . | . . 4 | 8 . 1
| . . . | 8 . . | 2 . 5 |
+-------+-------+-------+
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Play this puzzle online
A couple of X-wings, a couple of ERs, and a LOT of XY-chains/wings. About 10 moves altogether for me. Maybe there's a shorter way.
(For those who like spotting these things: there's a 6-point X-cycle early on - or 7-point loop with discontinuity if you prefer. It gets absorbed anyway by the XY-things.)
And I found an M-wing, but that wasn't necessary either. One of the XY-chains was slightly different - a 4-point loop with one arm diagonally in a box. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sun Mar 30, 2008 9:31 pm Post subject: Re: Don't . . . |
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| Victor wrote: | | [don't]. . . do this unless you like |
... to swim across the Danube on Jan.1st
... to cross the desert and walk around each oasis on the way
... to put on shoes two sizes too small and go for a 6 hour walk on concrete
You get my drift. I gave up.
I thought I must have made a mistake somewhere.
nope.
It is a long and winding road that leads (not to your door but)
to so much more of the same...
exhausted. |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sun Mar 30, 2008 10:21 pm Post subject: difficult |
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A w-wing (63), eliminating 6's was a key move for me.
Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Mar 31, 2008 12:26 am Post subject: |
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I don't know where you guys find all these moves, but after basics I got stuck here and couldn't see a thing. But a couple of extended Medusa iterations did the trick.
| Code: |
+------------------+-----------------+------------+
| 6 2 7 | 4 39 15 | 15 8 39 |
| 3 8 5 | 169 679 2 | 14 469 679 |
| 49 1 49 | 356 8 3567 | 35 2 367 |
+------------------+-----------------+------------+
| 189 5 169 | 1269 4 169 | 7 3 28 |
| 1489 349 1349 | 7 239 139 | 6 5 28 |
| 7 36 2 | 36 5 8 | 9 1 4 |
+------------------+-----------------+------------+
| 2 3469 8 | 3569 1 3569 | 34 7 369 |
| 5 3679 369 | 2369 23679 4 | 8 69 1 |
| 149 34679 13469 | 8 3679 3679 | 2 469 5 |
+------------------+-----------------+------------+
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Play this puzzle online at the Daily Sudoku site |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Mon Mar 31, 2008 10:13 am Post subject: |
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Marty, you copied it wrong here, the 6 is given in r5c6.
After x-wing for 1:
| Code: | *------------------------------------------------------------*
| 6 29 7 | 4 39 15 | 15 8 239 |
| 3 8 5 | 169 679 2 | 467 1469 679 |
| 249 1 49 | 3569 8 37 | 367 25 23679 |
|---------------------+------------------+-------------------|
| 189 5 1689 | 29 4 19 | 67 3 2678 |
| 1489 349 13489 | 7 239 6 | 15 25 28 |
| 7 36 2 | 13 5 8 | 9 16 4 |
|---------------------+------------------+-------------------|
| 2489 2469 4689 | 2569 1 59 | 346 7 369 |
| 5 23679 369 | 2369 23679 4 | 8 69 1 |
| 149 34679 13469 | 8 3679 37 | 2 469 5 |
*------------------------------------------------------------* |
xy-chain in boxes 345:
r4c4=9, r4c6=1, r6c4=3, r6c2=6, r6c8=1, r6c7=5, r5c8=2 => r4c9<>2, r5c5<>2
With coloring in 3 and ER for 6 i get here:
| Code: | *--------------------------------------------------------*
| 6 29 7 | 4 39 15 | 15 8 239 |
| 3 8 5 | 169 6-7 2 | 467 1469 679 |
| 249 1 49 | 3569 8 @37 | 367 25 23679 |
|--------------------+---------------+-------------------|
| 189 5 1689 | 2 4 19 | 67 3 678 |
| 1489 349 1489 | 7 39 6 | 15 25 28 |
| 7 #36 2 |#13 5 8 | 9 16 4 |
|--------------------+---------------+-------------------|
| 2489 249 4689 | 569 1 59 | 346 7 369 |
| 5 7 369 |#369 2 4 | 8 69 1 |
| 149 @469 13469 | 8 @67 #3-7 | 2 469 5 |
*--------------------------------------------------------* |
A useless kite for 3: r6c2=3 or r9c6=3
r9c6=3 => r3c6=7
r6c2=3 => r9c2=6 => r9c5=7
xy-wing later solves it. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Mar 31, 2008 3:49 pm Post subject: |
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| Quote: | | Marty, you copied it wrong here, the 6 is given in r5c6. |
This is quite fascinating. I clicked the link under the grid in Victor's post and the 6 wasn't there, but it was in r5c7. Would someone else try that and see if they see the same thing? If others see the same maybe I'll contact Sam.
I guess I'll try the puzzle again.
Thanks for pointing that out. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Mon Mar 31, 2008 4:08 pm Post subject: |
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Sorry Marty, it's not fascinating - it's down to my carelessness. When I checked, I realised that I'd copied wrongly from the original, corrected it on the displayed grid, and forgot that that wasn't quite enough.
Here's the correct version:
| Code: |
+------------------+---------------+----------------+
| 6 29 7 | 4 39 15 | 15 8 239 |
| 3 8 5 | 169 679 2 | 467 1469 679 |
| 249 1 49 | 3569 8 37 | 367 25 23679 |
+------------------+---------------+----------------+
| 189 5 1689 | 129 4 19 | 67 3 2678 |
| 1489 349 13489 | 7 239 6 | 15 125 28 |
| 7 36 2 | 13 5 8 | 9 16 4 |
+------------------+---------------+----------------+
| 2489 2469 4689 | 2569 1 59 | 346 7 369 |
| 5 23679 369 | 2369 23679 4 | 8 69 1 |
| 149 34679 13469 | 8 3679 37 | 2 469 5 |
+------------------+---------------+----------------+
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Play this puzzle online |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Mar 31, 2008 9:42 pm Post subject: |
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| Thanks Victor, we all do that, I'm just glad that there's not a crazy xx with the site. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Tue Apr 01, 2008 11:22 am Post subject: |
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Thanks Marty. Pity I didn't do it a couple of days later - it would have made a good April Fool's.
PS. I've tried the ersatz version without much success - serious stuff. Congratulations on solving it! |
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