| View previous topic :: View next topic |
| Author |
Message |
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
 Posted: Fri Feb 25, 2011 7:09 pm Post subject: Free Press Feb 25, 2011 |
 |
|
Not yet done. Does require advanced moves.
| Code: |
+-------+-------+-------+
| 7 . 1 | . . . | . . . |
| . 9 . | . . . | . 1 . |
| . 8 2 | . 3 . | 7 . . |
+-------+-------+-------+
| . . . | 1 . 5 | 3 2 . |
| . . . | 9 7 . | . . . |
| . 1 4 | 6 . 2 | . . . |
+-------+-------+-------+
| . . 6 | . 9 . | 1 5 . |
| . 5 . | . . . | . 9 . |
| . . . | . . . | 4 . 6 |
+-------+-------+-------+
|
Play this puzzle online at the Daily Sudoku site
Keith |
|
| Back to top |
|
 |
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Fri Feb 25, 2011 7:55 pm Post subject: |
|
|
I used three steps. Don't know if the first was needed, but the second set up the third.
| Quote: | Type 6 UR (12)
XY-Chain; r2c7<>2
XY-Wing (583); r1c2, r2c9<>3 |
|
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Sat Feb 26, 2011 3:20 am Post subject: |
|
|
| Code: | +---------------+-----------------+--------------+
| 7 34 1 | 2458 6 9 | 258 D38 234 |
| 6 9 35 | 24578 25 A478 | 258 1 234 |
| 45 8 2 | 45 3 1 | 7 6 9 |
+---------------+-----------------+--------------+
| 9 6 7 | 1 4 5 | 3 2 8 |
| 58 2 58 | 9 7 3 | 6 4 1 |
| 3 1 4 | 6 8 2 | 9 7 5 |
+---------------+-----------------+--------------+
| 248 347 6 | 3478 9 X478 | 1 5 237 |
| 1248 5 38 | 3478 12 6 | 28 9 237 |
| 12 37 9 | 25 125 B78 | 4 C38 6 |
+---------------+-----------------+--------------+ |
A,B,C,D would form a skyscraper on 8's if the 8 at X was false.
this skyscraper would in turn eliminate the 8 at r2c7 and r1c4
if the 8 that is preventing the skyscraper at X is true then we can find logic to prove the 8 at r2c7 and r1c4 can't exist anyways.
[skyscraper(8):...r2c6=r9c6 - r9c8 = r1c8] = (8-4)r7c6 = (4)r2c6 - (4)r3c4 = (4)r3c1 - (4=3)r1c2 - (3=8)r1c8
| Code: | +----------------+-------------------+-----------------+
| 7 (34) 1 | 245-8 6 9 | 258 (38) 234 |
| 6 9 35 | 24578 25 7(48) | 25-8 1 234 |
| 5(4) 8 2 | 5(4) 3 1 | 7 6 9 |
+----------------+-------------------+-----------------+
| 9 6 7 | 1 4 5 | 3 2 8 |
| 58 2 58 | 9 7 3 | 6 4 1 |
| 3 1 4 | 6 8 2 | 9 7 5 |
+----------------+-------------------+-----------------+
| 284 347 6 | 3478 9 7(48) | 1 5 237 |
| 1248 5 38 | 3478 12 6 | 28 9 237 |
| 12 37 9 | 25 125 7(8) | 4 3(8) 6 |
+----------------+-------------------+-----------------+ |
and the puzzle is solved. |
|
| Back to top |
|
|
peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
|
| Posted: Sat Feb 26, 2011 10:24 am Post subject: |
|
|
A simple ANP provides another one-stepper...
| Code: | | anp(25=8)r2c57 - (8=3)r1c8 - (3=4)r1c2 - (4=5)r3c1 ; r2c3<>5 |
|
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Sat Feb 26, 2011 4:41 pm Post subject: |
|
|
| peterj wrote: | A simple ANP provides another one-stepper...
|
It scares me when someone thinks an ANP() is simple. _  _ |
|
| Back to top |
|
|
tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
|
| Posted: Sat Feb 26, 2011 10:04 pm Post subject: |
|
|
It is hard to match the wonderful "almost skyscraper" and the "simple ANP". After some looking, the best I could come up with is an ANT(245=8) in r1c4|r2c5|r3c4 (or using Dannys' notation: in b2q15).
ANT(245=8)r1c4|r2c5|r3c4-(8=3)r1c8-(3=4)r1c2-r3c1=(4)r3c4; r2c46<>4
Ted |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Sun Feb 27, 2011 12:11 am Post subject: |
|
|
Simpler is better?
After basics: | Code: | +-------------------+-------------------+-------------------+
| 7 34 1 | 2458 6 9 | 258 38 234 |
| 6 9 35 | 24578 25 478 | 258 1 234 |
| 45 8 2 | 45 3 1 | 7 6 9 |
+-------------------+-------------------+-------------------+
| 9 6 7 | 1 4 5 | 3 2 8 |
| 58 2 58 | 9 7 3 | 6 4 1 |
| 3 1 4 | 6 8 2 | 9 7 5 |
+-------------------+-------------------+-------------------+
| 248 347 6 | 3478 9 478 | 1 5 237 |
| 1248 5 38 | 3478 12 6 | 28 9 237 |
| 12 37 9 | 25 125 78 | 4 38 6 |
+-------------------+-------------------+-------------------+ |
There is an X-wing on 4 in R38, and a Type 6 UR that solves R5C5, R9C1 = 1. Leaving us here: | Code: | +----------------+----------------+----------------+
| 7 34 1 | 258@ 6 9 | 258@ 3-8 234 |
| 6 9 35 | 2578 25@ 478 | 258@ 1 234 |
| 45 8 2 | 45 3 1 | 7 6 9 |
+----------------+----------------+----------------+
| 9 6 7 | 1 4 5 | 3 2 8 |
| 58 2 58 | 9 7 3 | 6 4 1 |
| 3 1 4 | 6 8 2 | 9 7 5 |
+----------------+----------------+----------------+
| 28 347 6 | 378 9 478 | 1 5 237 |
| 248 5 38 | 3478 1 6 | 28 9 237 |
| 1 37 9 | 25@ 25@ 78 | 4 38 6 |
+----------------+----------------+----------------+ |
The 25 DP labeled @ removes 8 from R1C8, solving the puzzle.
Keith |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
