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Puzzle 11/05/23: ~ Extreme BBDB!!!

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Mon May 23, 2011 4:40 pm    Post subject: Puzzle 11/05/23: ~ Extreme BBDB!!! Reply with quote

Code:
 +-----------------------+
 | . 6 3 | . . 5 | . . 4 |
 | 9 8 . | 4 . 6 | . . 2 |
 | 4 . . | 9 . 3 | . . . |
 |-------+-------+-------|
 | . 9 8 | 5 . 7 | . . . |
 | . . . | . 3 . | 9 . . |
 | 3 5 6 | 2 . 9 | . 8 7 |
 |-------+-------+-------|
 | . . . | . 5 . | . . . |
 | . . . | . . 4 | . 5 9 |
 | 5 3 . | . . 2 | . 4 8 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Mon May 23, 2011 6:31 pm    Post subject: Reply with quote

Ouch Exclamation Exclamation

I may be some time...
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JC Van Hay



Joined: 13 Jun 2010
Posts: 364
Location: Charleroi, Belgium

PostPosted: Tue May 24, 2011 7:58 am    Post subject: Reply with quote

Entertaining puzzle ...
Quote:
Mutant Swordfish (Extended Kite) : 1R6C6B9/1B4R7C7 => -1r4c5,-1r5c4;-1r7c4;-1r12347c7
Triple ER : 1B452 => 1r4c1=1r1c4 => -1r1c1; Claiming(1)B24 : -1r23c5,-1r5c2
Kite 6R9C5 => -6r4c7
Skyscraper 6R59 => -6r7c8

8r7c6=8r5c6-(8=6)r5c4-6r789c4=6r8c5-6r8c1=6r7c1 => -8r7c1
L2 Wing (18) 1R1,1B5,8R5 => -8r1c4
XY Wing (-167) R9C34,R8C5 => -1r8c23
BUG+1 => +2r4c8
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue May 24, 2011 8:09 am    Post subject: Reply with quote

This was pretty tough! No desperately hard moves (that's relative I know) but so many paths and dead-ends. The good thing was that you only had to concentrate on one digit!
Quote:
#1 colouring/grouped x-chains ; (1)r1c4=r123c5 { -r6c5=r6c7* } - r46c5=r5c46 - r5c12=r4c1 ; *r1c7<>1, r1c1<>1
#2 w-wing(18) ; (1=8)r1c4 - r5c4=r5c6 - (8=1)r7c6 ; r789c4<>1
#3 almost xy-wing ; (1)r9c3=r9c7 - r6c7=r6c5 - anp(1=28)r13c5 - (8)r8c5=xywing(67-1)[(1=6)r8c5-(6=7)r9c4-(7=1)r9c3] ; r8c23<>1
#4 x-wing(1) r6, r8 ; r4c5<>1, r24c7<>1
#5 BUG+1 ; r4c8=2

At each step there seemed to be a bunch of dead-end turbot moves on 1, perhaps there is some monster fish lurking that I missed...

Danny, nice to have a tough one now and again - thanks.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue May 24, 2011 3:30 pm    Post subject: Reply with quote

Yes, because of the way I have my puzzle generator configured for the forum, the only way to get an extreme puzzle is to have a mandatory Swordfish or larger present. As Peter indicated, almost every step can be based on eliminations in <1>.

Code:
 after basics
 +-----------------------------------------------------------------------+
 |  127    6      3      |  178    1278   5      |  178    9      4      |
 |  9      8      157    |  4      17     6      |  1357   137    2      |
 |  4      127    1257   |  9      1278   3      |  15678  167    16     |
 |-----------------------+-----------------------+-----------------------|
 |  12     9      8      |  5      146    7      |  12346  1236   136    |
 |  127    127    4      |  168    3      18     |  9      126    5      |
 |  3      5      6      |  2      14     9      |  14     8      7      |
 |-----------------------+-----------------------+-----------------------|
 |  68     4      9      |  13678  5      18     |  12367  12367  136    |
 |  68     127    127    |  13678  1678   4      |  1367   5      9      |
 |  5      3      17     |  167    9      2      |  167    4      8      |
 +-----------------------------------------------------------------------+
 # 91 eliminations remain

JC found the smallest fish for a large number of eliminations:

Code:
 mutant  Swordfish r6c6b9\r7c7b5  =>  r57c4,r4c5,r12347c7<>1

There's a larger fish that doesn't mix rows and columns for the same eliminations:

Code:
 Franken Jellyfish c689b4\r457b3  =>  r57c4,r4c5,r12347c7<>1

This exposes another fish:

Code:
 finned Franken Swordfish r146\c15b6  =>  r23c5<>1

Code:
 after the dust settles
 +-----------------------------------------------------------------------+
 |  27     6      3      |  18     128    5      |  78     9      4      |
 |  9      8      15     |  4      7      6      |  35     13     2      |
 |  4      127    1257   |  9      28     3      |  5678   167    16     |
 |-----------------------+-----------------------+-----------------------|
 |  12     9      8      |  5      46     7      |  2346   1236   136    |
 |  127    27     4      |  68     3      18     |  9      126    5      |
 |  3      5      6      |  2      14     9      |  14     8      7      |
 |-----------------------+-----------------------+-----------------------|
 |  68     4      9      |  3678   5      18     |  2367   12367  136    |
 |  68     127    127    |  13678  168    4      |  1367   5      9      |
 |  5      3      17     |  167    9      2      |  167    4      8      |
 +-----------------------------------------------------------------------+
 # 72 eliminations remain

 XY-Chain: (1=8)r1c4 - (8=6)r5c4 - (6=4)r4c5 - (4=1)r6c5  =>  r1c5<>1

 <67+1>  XY-Wing  r9c4/r8c5+r9c3         <> 1    r8c23

         BUG+1                           =  2    r4c8

Not bad for a puzzle with 34 givens, and none of them <1>. _ Very Happy _
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