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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Thu Dec 18, 2008 3:23 am Post subject: Ad Hoc Puzzle 1 |
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I ran across this puzzle while experimenting with my puzzle generator. Anyone find it interesting?
| Code: | +-----------------------+
| . . 1 | 9 7 . | 5 3 . |
| . 7 . | . . 2 | . . . |
| 9 . 4 | . . . | . . . |
|-------+-------+-------|
| 1 . . | 2 . 9 | 3 . . |
| 8 . . | . 1 . | . 9 . |
| . 9 . | 6 . 8 | 7 1 . |
|-------+-------+-------|
| 7 . . | 4 . 5 | . . . |
| 4 . . | . 9 7 | . . 3 |
| . . . | . . . | . 7 1 |
+-----------------------+
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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
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| Posted: Thu Dec 18, 2008 6:21 am Post subject: |
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| Quote: | | Anyone find it interesting? |
Yes. And difficult. I was stuck after a couple of ERs and a Finned X-Wing and had to turn to my Medusa crutch. That opened things up just enough to finish it off with a Type 6 UR, a W-Wing and simple coloring. Took me over an hour.
(Be pretty embarrassing when someone reports their one-stepper). |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Dec 18, 2008 8:17 am Post subject: |
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| Code: | .---------------------.---------------------.---------------------.
| 26 268 1 | 9 7 46 | 5 3 2468 |
| 356 7 3568 | 358 3468 2 | 1 468 9 |
| 9 23568 4 | 358 368 1 | 268 268 7 |
:---------------------+---------------------+---------------------:
| 1 456 7 | 2 45 9 | 3 468 4568 |
| 8 23456 2356 | 7 1 34 | 26 9 2456 |
| 235 9 235 | 6 345 8 | 7 1 245 |
:---------------------+---------------------+---------------------:
| 7 1 2368 | 4 2368 5 | 9 268 268 |
| 4 268 268 | 1 9 7 | 268 5 3 |
| 2356 23568 9 | 38 2368 36 | 4 7 1 |
'---------------------'---------------------'---------------------' |
| Quote: | I think its interesting because coloring takes it a long way.
1. coloring 4... r6c9 = r6c5 - r2c5 = r1c6; r1c9 <> 4
2. coloring 3... r3c2 = r9c2 - r7c3 = r7c5; r3c5 <> 3
3. coloring 8... r8c7 = r3c7 - r1c9 = r1c2; r8c2 <> 8
4. skyscraper 8... r1c2 = r9c2 - r9c4 = r2c4; r2c3 <> 8
5. coloring 6... r7c3 = r7c8 - r4c8 = r5c7; r5c3 <> 6
6. 45URr46c59[(8)r4c9 = (2)r6c9] - (2)r7c9 = (2)r7c8 - (2=8)r3c8; r4c8 <> 8 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Dec 18, 2008 3:42 pm Post subject: |
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Once again, I seemed to require more steps that others; a total of eight. Single digit techniques (coloring, kites, ER, skyscraper) worked, but I also got stuck until I finally found multi-coloring <8> that open everything up. I only used two two-digit steps: a Type 4 UR and a xy-wing.
| Marty R. wrote: | | Took me over an hour. |
Don't feel bad Marty. I also required at least an hour.
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Dec 18, 2008 3:57 pm Post subject: |
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| Code: | Techniques Used: basics, 3x 2-String Kite, 3x Skyscraper, XY-Wing
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I'm glad you (plural) found it interesting. However, since no one called it a fun puzzle, I will (try to) not post any more like this one. Thanks for the feedback!
[Edit: specifically identified which you.]
Last edited by daj95376 on Thu Dec 18, 2008 4:55 pm; edited 1 time in total |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Dec 18, 2008 4:35 pm Post subject: |
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| daj95376 wrote: | | Code: | Techniques Used: basics, 3x 2-String Kite, 3x Skyscraper, XY-Wing
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I'm glad you found it interesting. However, since no one called it a fun puzzle, I will (try to) not post any more like this one. Thanks for the feedback! |
Danny, I did like the puzzle and thought it was a fun variation from puzzles with lots of bivalue cells. It was not something I would prefer as a steady diet but an occasional one would be great.
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Dec 18, 2008 4:58 pm Post subject: |
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| Quote: | | coloring 4... r6c9 = r6c5 - r2c5 = r1c6; r1c9 <> 4 |
Norm, could you explain how we get from r6c5 to r1c6? A kite emanating from box 5 makes the same elimination, but I still would like to understand your method. I can understand that if r6c9=4, then r6c5 doesn't and that's where I stop. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Dec 18, 2008 6:44 pm Post subject: |
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I don’t believe this – it’s like a miraculous revelation. A couple of years ago I tried learning W-wings but couldn’t understand the explanations – complex arrays of big G’s and little g’s, big W’s and little w’s. I thought I’d give it another shot today after progressing so far with this puzzle before getting stuck. I found this simple explanation from Keith.
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=2008&sid=ca6ec00f3a2f9c52f1604e512708f40b
Now unless I am wrong, using a w wing, R1C2 cannot be a <2>. I used this method 3 times after this. Finished the thing in no time. Way, way easier than xy-wings.
Have I misunderstood? Seems far too elementary my Dear Watson!
| Code: |
+---------+-------+-------+
| 26 28 . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+---------+-------+-------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+---------+-------+-------+
| . . . | . . . | . . . |
| . 26 . | . . . | . . . |
| . . . | . . . | . . . |
+---------+-------+-------+
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Dec 18, 2008 7:40 pm Post subject: |
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| Marty R. wrote: | | Quote: | | coloring 4... r6c9 = r6c5 - r2c5 = r1c6; r1c9 <> 4 |
Norm, could you explain how we get from r6c5 to r1c6? A kite emanating from box 5 makes the same elimination, but I still would like to understand your method. I can understand that if r6c9=4, then r6c5 doesn't and that's where I stop. |
Marty,
would it make more sense if I used the 4 in r2c8 in stead of the 4 in r1c6?
in other words, do you see the skyscraper easier in rows 2 and 6? on candidate 4?
the 4's in row 6 and the 4's in row 2 form a skyscraper which eliminate the 4 in r1c9 and r4c8. is that easier for you to see? |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Dec 18, 2008 8:03 pm Post subject: |
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| Quote: | | Now unless I am wrong, using a w wing, R1C2 cannot be a <2>. |
Craig,
if you can show what makes either of the 2's in the (2,6) cells true, then I will tell you that you reached w-wing status.
but it seems to me like you missed explaining how the 6's are connected.
the classic w-wing involves 6 total candidates. your ending 2's and four 6's.
and looking at your diagram, you are missing two strongly linked 6's that reside outside the two (2,6) cells.
| Code: | 6 = strong link = 6
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(2=6)...............(6=2) |
as you can see from the diagram, the strongly linked 6's each see one of the (2,6) cells.
this is the w-wing you are trying to form, can you show which 6's are strongly linked? |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Dec 18, 2008 8:36 pm Post subject: |
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Yeah thanks Norman - I thought it had to be harder than I thought (if you know what I mean). I missed out on the strong link thing. That would be like a Type 4 UR - I think. I'll work on it.
Cheers |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Dec 18, 2008 10:33 pm Post subject: |
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| Quote: | Marty,
would it make more sense if I used the 4 in r2c8 in stead of the 4 in r1c6?
in other words, do you see the skyscraper easier in rows 2 and 6? on candidate 4?
the 4's in row 6 and the 4's in row 2 form a skyscraper which eliminate the 4 in r1c9 and r4c8. is that easier for you to see? |
Norm, yes, the skyscraper is evident. I was unable to follow what I thought was a conventional coloring chain.
Thanks. |
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