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Puzzle 10/05/23: (C) Advanced

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daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun May 23, 2010 3:07 pm Post subject: Puzzle 10/05/23: (C) Advanced

Code:

+-----------------------+
| 1 7 6 | 8 . . | 2 . . |
| 5 2 . | . . . | 1 . . |
| 3 . 8 | . . 6 | . . . |
|-------+-------+-------|
| 4 . . | 6 . 1 | . . 3 |
| . . . | . 3 . | 4 . 1 |
| . . 3 | 9 . 4 | 6 2 . |
|-------+-------+-------|
| 8 4 . | . 6 2 | . . . |
| . . . | . . 3 | . . . |
| . . . | 4 9 . | . . 2 |
+-----------------------+

Play this puzzle online at the Daily Sudoku site

peterj

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

Posted: Sun May 23, 2010 5:55 pm Post subject:

A somewhat contrived single-stepper...

Quote:

"Almost" xy-chain depending on r5c7
<>9: xy-chain (7=1)r9c3-(1=5)r9c8-(5=8)r5c8-(8=7); r9c6<>7
=9: -(9=2)r5c1-(2=9)r8c1-(9=8)r8c7-(8=5)r9c7-(5=1)r9c8-(1=7)r9c3; r9c6<>7

You could probably also see it as a chain which splits and joins again at r5c7.

My first pass was two steps using a kite but went back (for fun?!) to see if I could use the chain in one go.

Luke451

Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

Posted: Mon May 24, 2010 5:01 pm Post subject:

peterj wrote:

"Almost" xy-chain depending on r5c8
<>9: xy-chain (7=1)r9c3-(1=5)r9c8-(5=8)r5c8-(8=7); r9c6<>7
=9: -(9=2)r5c1-(2=9)r8c1-(9=8)r8c7-(8=5)r9c7-(5=1)r9c8-(1=7)r9c3; r9c6<>7

Don't know how you spotted that, but it works fine! Here's it cutnpasted into one chain:

Code:

*--------------------------------------------------*
| 1 7 6 | 8 4 5 | 2 3 9 |
| 5 2 4 | 3 7 9 | 1 68 68 |
| 3 9 8 | 12 12 6 | 57 457 45 |
|----------------+----------------+----------------|
| 4 8 259 | 6 25 1 | 579 579 3 |
| 29 6 259 | 27 3 78 | 4 589 1 |
| 7 1 3 | 9 58 4 | 6 2 58 |
|----------------+----------------+----------------|
| 8 4 19 | 5 6 2 | 3 19 7 |
| 29 5 279 | 17 18 3 | 89 46 46 |
| 6 3 17 | 4 9 78 | 58 15 2 |
*--------------------------------------------------*

(7=8)r5c6-(8)r5c8=xy chain[(5=9)r5c8-(9=2)r5c1-(2=9)r8c1-(9=8)r8c7-(8=5)r9c7]-(5=1)r9c8-(1=7)r9c3 =>r9c6<>7

To me, there's a lesson here. When one's xy-chain hits a dead end, take a quick look for any "almost" possibilities.

Marty R.

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

Posted: Tue May 25, 2010 4:23 am Post subject:

I used an X-Wing on 1 which was useless, then two W-Wings, both on 58 (different pairs) and both flightless with pincer transport.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue May 25, 2010 10:18 am Post subject:

Code:

c17r8 Skyscraper <> 9 r4c3,r5c8

Code:

<29> UR r58c13 => r5c3=5 and/or r8c3=7

r5c3=5 r4c3=2 => r5c1=9 r8c1=2
r8c3=7 r9c3=1 r7c3=9 => r8c1=2 r5c1=9
+-----------------------------------------------------+
| 1 7 6 | 8 4 5 | 2 3 9 |
| 5 2 4 | 3 7 9 | 1 68 68 |
| 3 9 8 | 12 12 6 | 57 457 45 |
|-----------------+-----------------+-----------------|
| 4 8 25 | 6 25 1 | 79 79 3 |
| 29 6 29+5 | 27 3 78 | 4 58 1 |
| 7 1 3 | 9 58 4 | 6 2 58 |
|-----------------+-----------------+-----------------|
| 8 4 19 | 5 6 2 | 3 19 7 |
| 29 5 29+7 | 17 18 3 | 89 46 46 |
| 6 3 17 | 4 9 78 | 58 15 2 |
+-----------------------------------------------------+
# 34 eliminations remain

Code:

BUG+1 = 5 r3c8

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