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Vanhegan extreme

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Marty R.

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

Posted: Thu Mar 01, 2012 4:23 pm Post subject: Vanhegan extreme

This is puzzle 6-631747, rated 2.4.0.1.1. I was able to solve it only by hacking away at it until my 13th move broke it open. I'm interested in seeing how others attack it.

Code:

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

Play this puzzle online at the Daily Sudoku site

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Thu Mar 01, 2012 9:50 pm Post subject:

Code:

+---------------------+----------------+------------------------+
| 8 4 6 | 1 39 39 | 7 5 2 |
| 3 2 1(9) | 8 5 7 | 169 4 169 |
| 5 1(9) 7 | 2 6 4 | -1(89) 18 3 |
+---------------------+----------------+------------------------+
| 17 189 3 | 5 4 6 | 2 178 19 |
| 4 156-89 15-8(9) | 7 2 (89) | 16-39(8) 136-8 156-9 |
| 67 5689 2 | 3 89 1 | 4 678 569 |
+---------------------+----------------+------------------------+
| 9 1356 15 | 4 7 2 | 136 136 8 |
| 16 7 18 | 9 18(3) 5 | 16(3) 2 4 |
| 2 138 4 | 6 138 (38) | 5 9 7 |
+---------------------+----------------+------------------------+

Loop{8r5c7=8r3c7-Kite(9r3c7=9r3c2-9r2c3=9r5c3)-(9=8)r5c6}-(8=3)r9c6-3r8c5=3r8c7

=> 8r3c7=9r3c7 : -1r3c7
9r3c7=9r5c3 : -9r5c7
9r5c3=9r5c6 : -9r5c279; +9r23c7 : -9r2c9
8r5c6=8r5c7 : -8r5c238; +8r8c3
8r5c7=3r8c7 : -3r5c7; +3r5c8

Kite(6R8C8) => -6r6c1; 6 singles; Kite(1R3C3) => -1r7c8; stte

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Thu Mar 01, 2012 10:55 pm Post subject:

FWIW:

Code:

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

c36r5 Skyscraper <> 8 r8c5,r9c2
r34c2 Skyscraper <> 9 r2c9,r5c7

+-----------------------------------------------------------------------+
| 8 4 6 | 1 39 39 | 7 5 2 |
| 3 2 c19 | 8 5 7 | d169 4 16 |
| 5 19 7 | 2 6 4 | e189 18 3 |
|-----------------------+-----------------------+-----------------------|
| 17 189 3 | 5 4 6 | 2 178 19 |
| 4 15689 b159 | 7 2 a89 | f1368 1368 1569 |
| 67 5689 2 | 3 89 1 | 4 678 569 |
|-----------------------+-----------------------+-----------------------|
| 9 1356 15 | 4 7 2 | 136 136 8 |
| 16 7 8 | 9 13 5 | 136 2 4 |
| 2 13 4 | 6 138 38 | 5 9 7 |
+-----------------------------------------------------------------------+
# 57 eliminations remain

4-SIS M-Ring: (8=9)r5c6 - r5c3 = r2c3 - r2c7 = (9-8)r3c7 = (8)r5c7 - loop =>
r5c2<>89; r3c7<>1; r5c8<>8; r5c9<>9

+--------------------------------------------------------------+
| 8 4 6 | 1 39 39 | 7 5 2 |
| 3 2 19 | 8 5 7 | 169 4 16 |
| 5 19 7 | 2 6 4 | 89 18 3 |
|--------------------+--------------------+--------------------|
| 17 189 3 | 5 4 6 | 2 178 19 |
| 4 156 159 | 7 2 d89 | e1368 136 156 |
| 67 5689 2 | 3 89 1 | 4 678 569 |
|--------------------+--------------------+--------------------|
| 9 1356 15 | 4 7 2 | 136 136 8 |
| 16 7 8 | 9 b13 5 | a136 2 4 |
| 2 13 4 | 6 138 c38 | 5 9 7 |
+--------------------------------------------------------------+
# 52 eliminations remain

S-Wing: (3)r8c7 = r8c5 - (3=8)r9c6 - r5c6 = (8)r5c7 => r5c7<>3

+--------------------------------------------------------------+
| 8 4 6 | 1 39 39 | 7 5 2 |
| 3 2 19 | 8 5 7 | 169 4 16 |
| 5 19 7 | 2 6 4 | 89 18 3 |
|--------------------+--------------------+--------------------|
| 17 189 3 | 5 4 6 | 2 178 19 |
| 4 156 159 | 7 2 89 | 168 3 156 |
| 67 5689 2 | 3 89 1 | 4 678 569 |
|--------------------+--------------------+--------------------|
| 9 1356 15 | 4 7 2 | 136 16 8 |
| 16 7 8 | 9 13 5 | 136 2 4 |
| 2 13 4 | 6 138 38 | 5 9 7 |
+--------------------------------------------------------------+
# 48 eliminations remain

c18r6 Skyscraper <> 6 r7c2,r8c7

c38r7 Skyscraper <> 1 r2c79,r3c2

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