dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Set H Puzzle 13

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj
View previous topic :: View next topic  
Author Message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Dec 26, 2008 10:01 pm    Post subject: Set H Puzzle 13 Reply with quote

Code:
 +-----------------------+
 | . . 2 | . 4 . | . . 7 |
 | . 8 . | . . . | 4 . . |
 | 1 . 6 | 3 . . | 2 . . |
 |-------+-------+-------|
 | . . 8 | . . . | 9 4 . |
 | 2 . . | . 9 . | . . 6 |
 | . . . | . . 3 | . . . |
 |-------+-------+-------|
 | . 2 7 | 9 . . | 6 . 1 |
 | . . . | 8 . . | . . . |
 | 3 . . | . 2 . | 7 . 9 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
Back to top
View user's profile Send private message
tlanglet



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

PostPosted: Sun Dec 28, 2008 12:35 am    Post subject: Reply with quote

I used six steps to solve this puzzle but have no idea what was really required; three steps were URs with overlaying x-wings!

Quote:
skyscraper <3>
ER <5>
UR <59> with x-wing <9>
UR <57> with x-wing <7>
UR <67> with x-wing <7>
xyz <156>

Ted
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Jan 02, 2009 8:30 am    Post subject: Reply with quote

Code:
.---------------------.---------------------.---------------------.
| 59     359    2     | 156    4      15689 | 1358   13569  7     |
| 7      8     *359   | 1256   156    12569 | 4      13569 *35    |
| 1      4      6     | 3      578    5789  | 2      59     58    |
:---------------------+---------------------+---------------------:
| 56     13567  8     | 12567  156    1256  | 9      4     *235   |
| 2      1357  *135   | 4      9      158   | 1358   1357   6     |
| 4      15679  159   | 12567  1568   3     | 158    157    258   |
:---------------------+---------------------+---------------------:
| 8      2      7     | 9      35     4     | 6      35     1     |
| 569    1569   159   | 8      13567  1567  | 35     2      4     |
| 3      156    4     | 156    2      156   | 7      8      9     |
'---------------------'---------------------'---------------------'

the marked skyscraper on 3's goes a long way.

then I found this mixed w-wing extended blah blah blah chain....
Code:
.------------------.------------------.------------------.
| 59    59    2    |*16    4     8    |*13    136   7    |
| 7     8     3    | 2    *16    9    | 4     16    5    |
| 1     4     6    | 3    *57   *57   | 2     9     8    |
:------------------+------------------+------------------:
| 56    1567  8    | 1567 -156   2    | 9     4     3    |
| 2     3     15   | 4     9    *15   | 8     7     6    |
| 4     67    9    | 67    8     3    | 15    15    2    |
:------------------+------------------+------------------:
| 8     2     7    | 9    *35    4    | 6    *35    1    |
| 569   1569  15   | 8     1357  1567 |*35    2     4    |
| 3     156   4    | 15    2     156  | 7     8     9    |
'------------------'------------------'------------------'

basically the strong links on 5 in row 3 connect the {3,5} cell in r7c5 and the {1,5} cell in r5c6, which makes either the 1 or the 3 true. do a little extening from the 3 and get this chain to elimate the 1 in r4c5 to solve it.

(1=5)r5c6 - (5)r3c6 = (5)r3c5 - (5=3)r7c5 - (3)r7c8 = (3)r8c7 - (3=1)r1c7 - (1)r1c4 = (1)r2c5; r4c5 <> 1
Back to top
View user's profile Send private message
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Fri Jan 02, 2009 7:42 pm    Post subject: Reply with quote

Or, that's a 9-cell XY-Chain.

Here's a shorter ALS Chain that does the trick:
(5)r4c4|(5)r89c6 - (5=1)r5c6 - ALS[(1)r4c5=(5)r4c15] - (5)r4c4=(5)r9c4 - (5)r4c4|(5)r89c6; r4c4|r89c6<>5

Descriptively, r5c6 is <5> or <1>. If <1>, the 56 naked pair in r4 means r4c4 is not <5> so r9c4 must be <5>. Thus, r5c6 and/or r9c4 must be <5>, eliminating <5> from r4c4 and r89c6.
Back to top
View user's profile Send private message Visit poster's website
cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Fri Jan 02, 2009 8:25 pm    Post subject: Reply with quote

6 steps like Ted - but I started with an ER on <3> that went a long way. Then an x wing on 7; Type 4 URs on 57 and 59; an ER on 5 and the xyz wing <156>.
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Mon Jan 05, 2009 2:15 am    Post subject: Reply with quote

Asellus wrote:
Or, that's a 9-cell XY-Chain.

Here's a shorter ALS Chain that does the trick:
(5)r4c4|(5)r89c6 - (5=1)r5c6 - ALS[(1)r4c5=(5)r4c15] - (5)r4c4=(5)r9c4 - (5)r4c4|(5)r89c6; r4c4|r89c6<>5

Descriptively, r5c6 is <5> or <1>. If <1>, the 56 naked pair in r4 means r4c4 is not <5> so r9c4 must be <5>. Thus, r5c6 and/or r9c4 must be <5>, eliminating <5> from r4c4 and r89c6.


very nice !! Cool
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group