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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Fri Oct 30, 2009 11:39 am Post subject: Puzzle NR_078 |
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| Code: | NR puzzles can be solved using these techniques:
Basics: Naked/Hidden Single, Naked Pair/Triple, Locked Candidates 1/2
Basics+: Naked Quad, Hidden Pair/Triple/Quad
VH: BUG+1, UR Type 1, X-Wing, XY-Wing
VH+: 2-String Kite, Empty Rectangle, Remote Pair, Skyscraper,
XYZ-Wing, finned X-Wing, UR Type 2/4
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| Code: | +-----------------------+
| . 5 . | . . 2 | 6 . . |
| 9 7 . | . . . | . 4 . |
| . . 3 | . 4 . | 9 . 2 |
|-------+-------+-------|
| . . . | 6 . . | . . . |
| . . 7 | . 1 9 | . . . |
| 5 . . | . 2 3 | 4 . . |
|-------+-------+-------|
| 3 . 4 | . . 6 | 2 . . |
| . 6 . | . . . | . 1 . |
| . . 9 | . . . | . . . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Fri Oct 30, 2009 6:44 pm Post subject: |
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A skyscraper 1 and skyscraper 8 left me here | Code: | *--------------------------------------------------------------------*
| 4 5 1 | 9 g37 2 | 6 f378 378 |
| 9 7 2 | 35 6 58 | 1 4 358 |
| 6 8 3 | 157 4 157 | 9 57 2 |
|----------------------+----------------------+----------------------|
| 1 34 8 | 6 57 457 | 357 2 9 |
| 2 d34 7 |c458 1 9 | 358 e3568 3568 |
| 5 9 6 | 78 2 3 | 4 78 1 |
|----------------------+----------------------+----------------------|
| 3 1 4 | 57 578 6 | 2 9 578 |
| 78 6 5 | 2 9 47 | 378 1 3478 |
| 78 2 9 |b13457 a3-578 1457 | 578 5678 45678 |
*--------------------------------------------------------------------*
(3)r9c5=(3-4)r9c4=(4)r5c4-(4=3)r5c2-(3)r5c8=(3)r1c8-(3)r1c5=(3)r9c5
=> r9c5=3;
singles
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat Oct 31, 2009 12:39 am Post subject: |
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I had 4 steps.
Kraken swordfish 1,
kite on 8,
x-wing on 5,
AIC using the UR 78 in r89c17; r8c7=3 or r9c7=5:
UR78[(5)r9c7 = (3)r8c7] - (3)r45c7 = (3)r5c89 - (3=4)r5c2 - (4=8)r5c4 - (8=7)r6c4 - (7=5)r7c4; r7c9, r9c56<>5.
Ted |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sat Oct 31, 2009 7:35 pm Post subject: |
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| Code: | +-------------+-------------------+---------------------+
| 4 5 1 | 9 37 2 | 6 378 378 |
| 9 7 2 | 35 6 8 | 1 4 35 |
| 6 8 3 | 157 4 157 | 9 57 2 |
+-------------+-------------------+---------------------+
| 1 34 8 | 6 57 457 | 35(7) 2 9 |
| 2 34 7 | 458 1 9 | 35(8) 356-8 356-8 |
| 5 9 6 | 78 2 3 | 4 (78) 1 |
+-------------+-------------------+---------------------+
| 3 1 4 | 57 578 6 | 2 9 578 |
| (78) 6 5 | 2 9 47 | 3(78) 1 3478 |
| (78) 2 9 | 13457 3578 1457 | 5(78) 5678 45678 |
+-------------+-------------------+---------------------+ |
something neat about the puzzle after the skyscapers on 1 and 8.
usually we would see that in the UR78 r89c17, the 3 in r8c7 and the 5 in r9c7 are strongly linked.
but we can also see that the 7 in r5c7 and the 8 in r6c7 are also strongly linked since they are the only outlets in the columns of the UR.
this creates a "naked pair" with the {7,8} cell in r6c8.
this eliminates the 8's in the rest of box 6.
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat Oct 31, 2009 9:00 pm Post subject: |
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Great observation Norm.
I noticed the UR 78 immediately after basics but could not make any use of it until later when the (35) worked in a chain.
Ted |
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