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Puzzle 10/03/17 ___ BBDB as VH+

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Mar 17, 2010 3:34 pm    Post subject: Puzzle 10/03/17 ___ BBDB as VH+ Reply with quote

Well, let's see if this BBDB hold up any better than the last one (cracked by Ted in three steps).

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

Play this puzzle online at the Daily Sudoku site
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tlanglet



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

PostPosted: Thu Mar 18, 2010 1:52 am    Post subject: Reply with quote

Four steps.

Quote:
Type 1 UR 18 in r15c23,
Type 1 UR 57 in r46c15,
flightless w-wing 49 r2c1 & r4c6 with strong link 4 in r5c146,
BUG+1 sets r5c6=4.

Ted
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Mar 18, 2010 4:41 am    Post subject: Reply with quote

Code:
+------------------+--------------------+-------------+
| 6      18  1348  | 345   35    48     | 2   9    7  |
| (49)   5   489   | 2479  279   2468-9 | 1   368  38 |
| 39     7   2     | 39    1     68     | 5   68   4  |
+------------------+--------------------+-------------+
| 57     2   39(4) | 8     57    (49)   | 39  1    6  |
| 39(4)  18  18    | 2349  6     249    | 39  7    5  |
| 57     6   39    | 3579  3579  1      | 8   4    2  |
+------------------+--------------------+-------------+
| 1      4   7     | 29    29    5      | 6   38   38 |
| 8      9   5     | 6     4     3      | 7   2    1  |
| 2      3   6     | 1     8     7      | 4   5    9  |
+------------------+--------------------+-------------+

1...w-wing {4,9} => r2c6 <> 9


Code:
+----------------+------------------+-------------+
| 6     18  1348 | 345   35    48   | 2   9    7  |
| (49)  5   48   | 7     2(9)  2468 | 1   368  38 |
| 39    7   2    | 3(9)  1     68   | 5   68   4  |
+----------------+------------------+-------------+
| 57    2   34   | 8     57    49   | 39  1    6  |
| 3-4   18  18   | (24)  6     249  | 39  7    5  |
| 57    6   9    | 35    357   1    | 8   4    2  |
+----------------+------------------+-------------+
| 1     4   7    | (29)  29    5    | 6   38   38 |
| 8     9   5    | 6     4     3    | 7   2    1  |
| 2     3   6    | 1     8     7    | 4   5    9  |
+----------------+------------------+-------------+

2...(4=9)r2c1 - (9)r2c5 = (9)r3c4 - (9=2)r7c4 - (2=4)r5c4; r5c1 <> 4
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Mar 18, 2010 11:23 am    Post subject: Reply with quote

Couple of interesting things following on from Norm's diagrams:

1)The <49> Wing actually removes not just the 9 but also the 4 from r2c6

2)Instead of Norm's final chain, a quick inspection of r1c3 shows that to avoid the deadly pattern r15c23<18> that cell must be either 3 or 4.

A locked pair <34> is formed with r4c3 and the 4 in r2c3 is toast and the puzzle is done.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Mar 18, 2010 6:38 pm    Post subject: Reply with quote

Mogulmeister wrote:
1)The <49> Wing actually removes not just the 9 but also the 4 from r2c6

Yes, the strong links on <4> means the W-Wing is also a generalized Remote Pair. Since I would have performed the 2-String Kite elimination on <4> prior to the W-Wing, I wouldn't have encountered the additional elimination.
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Marty R.



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

PostPosted: Thu Mar 18, 2010 10:21 pm    Post subject: Reply with quote

Quote:
2)Instead of Norm's final chain, a quick inspection of r1c3 shows that to avoid the deadly pattern r15c23<18> that cell must be either 3 or 4.

A locked pair <34> is formed with r4c3 and the 4 in r2c3 is toast and the puzzle is done.

That, of course, has the same effect as Ted's Type 1 UR.

I missed some basics since I didn't have the Type 1 on 18 available. But it was a Hidden UR on 18 which opened things up and I used a total of six moves.
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Mar 18, 2010 10:23 pm    Post subject: Reply with quote

Indeed but it was interesting that I came to it after Norm's initial removal of 9's and that makes it a 2 stepper but one that finishes in a different fashion.

Last edited by Mogulmeister on Thu Mar 18, 2010 10:36 pm; edited 3 times in total
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Mar 18, 2010 10:27 pm    Post subject: Reply with quote

daj95376 wrote:
Mogulmeister wrote:
1)The <49> Wing actually removes not just the 9 but also the 4 from r2c6

Yes, the strong links on <4> means the W-Wing is also a generalized Remote Pair. Since I would have performed the 2-String Kite elimination on <4> prior to the W-Wing, I wouldn't have encountered the additional elimination.


Absolutely - its just that I still don't include kites and skyscrapers in basics.
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