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Set H Puzzle 25

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Dec 30, 2008 7:23 am    Post subject: Set H Puzzle 25 Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Wed Dec 31, 2008 12:50 am    Post subject: Reply with quote

Took me five steps, UR, XY-Wing, W-Wing, multi-coloring and Remote Pairs.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Dec 31, 2008 8:31 am    Post subject: Reply with quote

Code:
.---------------------.---------------------.---------------------.
| 37     1      9     | 4      356    8     | 35     2      67    |
| 4      6      78    | 135    2     *15    | 135    9      78    |
| 2      35     358   | 136    9      7     | 13     4      68    |
:---------------------+---------------------+---------------------:
| 8   U[3]45    135   | 9   U[1]45    6     | 2      7    *-35    |
| 137    9      1357  |*15     8      2     | 4      6     *35    |
| 6     U45     2     | 7     U45     3     | 8      1      9     |
:---------------------+---------------------+---------------------:
| 9      2      13    | 13568  1356   15    | 7      58     4     |
| 5      8      6     | 2      7      4     | 9      3      1     |
| 13     7      4     | 1358   135    9     | 6      58     2     |
'---------------------'---------------------'---------------------'

the UR on {4,5} r46c25 says (3)r4c2 = (1)r4c5
so lets use that...
step 1...45UR[(3)r4c2 = (1)r4c5] - (1=5)r5c4 - (5)r5c9 = (5)r4c9; r4c9 <> 3

Code:
.---------------------.---------------------.---------------------.
| 37     1      9     | 4      356    8     | 35     2      67    |
| 4      6      78    |U13[5]  2      15    |U13[5]  9      78    |
| 2     *35    *58    |U13[6]  9      7     |U13     4     *68    |
:---------------------+---------------------+---------------------:
| 8     *34    *13    | 9      14     6     | 2      7      5     |
| 17     9      57    | 15     8      2     | 4      6      3     |
| 6      45     2     | 7      45     3     | 8      1      9     |
:---------------------+---------------------+---------------------:
| 9      2     *13    | 13568  1356  -15    | 7      58     4     |
| 5      8      6     | 2      7      4     | 9      3      1     |
| 13     7      4     | 1358   135    9     | 6      58     2     |
'---------------------'---------------------'---------------------'

the 13UR in r23c47 says that if 6 is not in r3c4 then the 5's have to exist in r2c47... 13UR[(6)r3c4 = (5)r2c47]...and vice versa...
huge chain can be formed from this to eliminate 1 from r7c7

step2...(1=3)r7c3 - (3)r4c3 = (3)r4c2 - (3=5)r3c2 - (5=8)r3c3 - (8=6)r3c9 - 13UR[(6)r3c4 = (5)r2c47] - (5=1)r2c6; r7c6 <> 1
obviously this is overkill.

brings this bug+3 grid
Code:
.---------------.---------------.---------------.
| 37   1    9   | 4    356  8   | 35   2    67  |
| 4    6    78  | 35   2    1   | 35   9    78  |
| 2    35   58  | 36   9    7   | 1    4    68  |
:---------------+---------------+---------------:
| 8    34   13  | 9    14   6   | 2    7    5   |
| 17   9    57  | 15   8    2   | 4    6    3   |
| 6    45   2   | 7    45   3   | 8    1    9   |
:---------------+---------------+---------------:
| 9    2    13  | 136  136  5   | 7    8    4   |
| 5    8    6   | 2    7    4   | 9    3    1   |
| 13   7    4   | 8    13   9   | 6    5    2   |
'---------------'---------------'---------------'

but coloring on 1's does the trick eliminates the 1 from r4c5.
step3...(1)......r4c3 = r7c3 - r9c1 = r9c5; r4c5 <> 1
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