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Brain Basher June 2

 
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sudocraz



Joined: 28 Apr 2008
Posts: 53

PostPosted: Thu Jun 04, 2009 2:59 pm    Post subject: Brain Basher June 2 Reply with quote

Hi All

Did anyone try the Brain Bashers Sudoku on June 2. My husband and I couldn't get anywhere with it. We don't know what we missed, but could only enter about 8 numbers in that puzzle. Confused
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Marty R.



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

PostPosted: Thu Jun 04, 2009 3:58 pm    Post subject: Reply with quote

I assume you mean the Super Hard. Here's a grid created hastily and I'm not sure if the basics are finished.

Code:

+--------------+--------------+----------------+
| 279 129 3    | 159 6    8   | 4     179 157  |
| 679 8   1679 | 4   157  3   | 15679 2   157  |
| 5   4   1679 | 19  127  27  | 1679  3   8    |
+--------------+--------------+----------------+
| 249 7   129  | 8   1234 5   | 12    6   1234 |
| 3   125 1258 | 16  124  246 | 1278  147 9    |
| 24  6   128  | 7   1234 9   | 128   5   1234 |
+--------------+--------------+----------------+
| 1   259 2579 | 3   8    47  | 2579  479 6    |
| 679 3   5679 | 2   457  1   | 579   8   457  |
| 8   25  4    | 56  9    67  | 3     17  1257 |
+--------------+--------------+----------------+

Play this puzzle online at the Daily Sudoku site
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Thu Jun 04, 2009 4:03 pm    Post subject: Reply with quote

I assume you mean the "Super Hard":
Code:
..3.6.4..
.8.4.3.2.
5.......8
.7.8.5.6.
3.......9
.6.7.9.5.
1.......6
.3.2.1.8.
..4.9.3..

I did this one, but I think I used a different chain than in the last two steps below.
After basics:
Code:
+-------------------+-------------------+-------------------+
| 279   129   3     | 159   6     8     | 4     179   157   |
| 679   8     1679  | 4     157   3     | 15679 2     157   |
| 5     4     1679  | 19    127   27    | 1679  3     8     |
+-------------------+-------------------+-------------------+
| 249   7     129   | 8     1234  5     | 12    6     1234  |
| 3     125   1258  | 16    124   246   | 1278  147   9     |
| 24    6     128   | 7     1234  9     | 128   5     1234  |
+-------------------+-------------------+-------------------+
| 1     259   2579  | 3     8     47    | 2579  479   6     |
| 679   3     5679  | 2     457   1     | 579   8     457   |
| 8     25    4     | 56    9     67    | 3     17    1257  |
+-------------------+-------------------+-------------------+

Note: Highlight (select) white boxes to see the text

Hint 1:
Quote:
X-wing on 4

Hint 2:
Quote:
X-wing on 9

Hint 3:
Quote:
X-wing on 1

Hint 4:
Quote:
XY-wing 15-7

Hint 5:
Quote:
XY-wing 1-56


By the way, when you ask Brain Basher to show you the solution, they actually explain it. Here's what they say for this one:
Quote:
R1C6 is the only square in row 1 that can be <8>
R3C8 is the only square in row 3 that can be <3>
R3C2 is the only square in row 3 that can be <4>
R9C1 is the only square in row 9 that can be <8>
R7C5 is the only square in row 7 that can be <8>
R7C4 is the only square in row 7 that can be <3>
Intersection of row 1 with block 1. The value <2> only appears in one or more of squares R1C1, R1C2 and R1C3 of row 1. These squares are the ones that intersect with block 1. Thus, the other (non-intersecting) squares of block 1 cannot contain this value.
R3C3 - removing <2> from <12679> leaving <1679>
Squares R5C6 and R7C6 in column 6 and R5C8 and R7C8 in column 8 form a Simple X-Wing pattern on possibility <4>. All other instances of this possibility in rows 5 and 7 can be removed.
R5C5 - removing <4> from <124> leaving <12>
Squares R1C2 and R7C2 in column 2 and R1C8 and R7C8 in column 8 form a Simple X-Wing pattern on possibility <9>. All other instances of this possibility in rows 1 and 7 can be removed.
R1C1 - removing <9> from <279> leaving <27>
R7C3 - removing <9> from <2579> leaving <257>
R1C4 - removing <9> from <159> leaving <15>
R7C7 - removing <9> from <2579> leaving <257>
R3C4 is the only square in column 4 that can be <9>
Squares R1C2 and R5C2 in column 2 and R1C4 and R5C4 in column 4 form a Simple X-Wing pattern on possibility <1>. All other instances of this possibility in rows 1 and 5 can be removed.
R5C3 - removing <1> from <1258> leaving <258>
R5C5 - removing <1> from <12> leaving <2>
R5C7 - removing <1> from <1278> leaving <278>
R1C8 - removing <1> from <179> leaving <79>
R5C8 - removing <1> from <147> leaving <47>
R1C9 - removing <1> from <157> leaving <57>
R3C6 is the only square in row 3 that can be <2>
R9C8 is the only square in column 8 that can be <1>
Intersection of column 6 with block 8. The value <7> only appears in one or more of squares R7C6, R8C6 and R9C6 of column 6. These squares are the ones that intersect with block 8. Thus, the other (non-intersecting) squares of block 8 cannot contain this value.
R8C5 - removing <7> from <457> leaving <45>
Squares R1C4 (XY), R3C5 (XZ) and R1C9 (YZ) form an XY-Wing pattern on <7>. All squares that are buddies of both the XZ and YZ squares cannot be <7>.
R3C7 - removing <7> from <167> leaving <16>
Squares R5C4 (XY), R5C2 (XZ) and R9C4 (YZ) form an XY-Wing pattern on <5>. All squares that are buddies of both the XZ and YZ squares cannot be <5>.
R9C2 - removing <5> from <25> leaving <2>
R1C1 is the only square in row 1 that can be <2>
R6C1 can only be <4>
R4C1 can only be <9>
R7C7 is the only square in row 7 that can be <2>
R4C7 can only be <1>
R4C3 can only be <2>
R3C7 can only be <6>
R6C7 can only be <8>
R5C7 can only be <7>
R6C3 can only be <1>
R5C8 can only be <4>
R5C6 can only be <6>
R4C9 can only be <3>
R6C5 can only be <3>
R3C3 can only be <7>
R5C2 can only be <5>
R6C9 can only be <2>
R4C5 can only be <4>
R3C5 can only be <1>
R7C3 can only be <5>
R2C1 can only be <6>
R1C4 can only be <5>
R8C5 can only be <5>
R5C3 can only be <8>
R7C2 can only be <9>
R5C4 can only be <1>
R9C6 can only be <7>
R7C8 can only be <7>
R1C2 can only be <1>
R8C3 can only be <6>
R7C6 can only be <4>
R1C8 can only be <9>
R9C9 can only be <5>
R8C1 can only be <7>
R2C3 can only be <9>
R8C7 can only be <9>
R8C9 can only be <4>
R2C5 can only be <7>
R9C4 can only be <6>
R2C7 can only be <5>
R1C9 can only be <7>
R2C9 can only be <1>


Keith


Last edited by keith on Thu Jun 04, 2009 6:00 pm; edited 1 time in total
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sudocraz



Joined: 28 Apr 2008
Posts: 53

PostPosted: Thu Jun 04, 2009 4:53 pm    Post subject: Reply with quote

Hi Keith & Marty

I did mean the superhard, forgot to mention that. Embarassed
The quotes didn't come out so I am off to the BB site.
I always do paper and pencil, so I didn't get any hints.

Thanks for the tips
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Thu Jun 04, 2009 4:55 pm    Post subject: Reply with quote

Here is, perhaps, a simpler solution.

The first X-wing takes out <4> in R5C5.

There is then a 4-cell chain (extended XY-wing, to some) 25, 56, 16, 12, that takes out <2> in R5C2.

That reveals an XY-wing 1-56 that solves R9C2, and the puzzle.

Keith
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Marty R.



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

PostPosted: Thu Jun 04, 2009 5:28 pm    Post subject: Reply with quote

Quote:
The quotes didn't come out so I am off to the BB site.

Sheila,

If you mean that you couldn't see what was within the quote, that's deliberate. Some people post solutions within the quote, then change the font color to white so people who don't want to see the answer won't see it. For those who want to see, just highlight (select) the text within the quote.
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sudocraz



Joined: 28 Apr 2008
Posts: 53

PostPosted: Thu Jun 04, 2009 5:37 pm    Post subject: Reply with quote

Hi Marty,

Thanks for telling me about the white quotes. I didn't know that.
I went back to BB and got the answer. I can't believe that both my husband and I missed the X-Wing. Shocked Too many other numbers out there, I suppose.
This was a good puzzle. We will both rework it tonight.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Jun 04, 2009 6:19 pm    Post subject: Reply with quote

for the chain gangers
after basics
Code:
.---------------------.---------------------.---------------------.
| 279    129    3     | 159    6      8     | 4      179    157   |
| 679    8      1679  | 4      157    3     | 15679  2      157   |
| 5      4      1679  | 19     127    27    | 1679   3      8     |
:---------------------+---------------------+---------------------:
| 249    7      129   | 8      1234   5     | 12     6      1234  |
| 3      125    1258  | 16     124    246   | 1278   147    9     |
| 24     6      128   | 7      1234   9     | 128    5      1234  |
:---------------------+---------------------+---------------------:
| 1      259    2579  | 3      8      47    | 2579   479    6     |
| 679    3      5679  | 2      457    1     | 579    8      457   |
| 8      25     4     | 56     9      67    | 3      17     1257  |
'---------------------'---------------------'---------------------'


focus on column 9
and the marked cells
Code:
+-------+-------+----------+
| . . . | . . . | . . 157  |
| . . . | . . . | . . 157  |
| . . . | . . . | . . 8    |
+-------+-------+----------+
| . . . | . . . | . .*1234 |
| . . . | . . . | . . 9    |
| . . . | . . . | . .*1234 |
+-------+-------+----------+
| . . . | . . . | . . 6    |
| . . . | . . . | . .*457  |
| . . . | . . . | . . 1257 |
+-------+-------+----------+

notice that if the 4 is false in r8c9, then the hidden pair {3,4} is true in r46c9
this leads to the 2's in r46c9 to be false...etc... leads to

Code:
.---------------------.---------------------.---------------------.
| 279    129    3     | 159    6      8     | 4      179    157   |
| 679    8      1679  | 4      157    3     | 15679  2      157   |
| 5      4      1679  | 19     127    27    | 1679   3      8     |
:---------------------+---------------------+---------------------:
| 249    7      129   | 8      1234   5     |*12     6     *1234  |
| 3      125    1258  | 16     124    246   |*1278   147    9     |
| 24     6      128   | 7      1234   9     |*128    5     *1234  |
:---------------------+---------------------+---------------------:
| 1      259    2579  | 3      8     *47    |*2579  -479    6     |
| 679    3      5679  | 2      457    1     | 579    8     *457   |
| 8     *25     4     |*56     9     *67    | 3      17    *1257  |
'---------------------'---------------------'---------------------'

hp= hidden pair
(4)r8c9 = (hp34-2)r46c9 = (2)r456c7 - (2)r7c7 = (2)r9c9 - (2=5)r9c2 - (5=6)r9c4 - (6=7)r9c6 - (7=4)r7c6; r7c8 <> 4
for a one stepper.
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tlanglet



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

PostPosted: Sat Jun 06, 2009 1:56 pm    Post subject: Reply with quote

I followed the sequence of steps already posted by others with two additions, which apparently were not helpful in solving the puzzle.

After the initial x-wing on 4, I found a Kraken x-wing that deleted 5 from r8c9.

Then I noted both a x-wing 9 and a Kraken x-wing 9. The Kraken also deleted 9 in two of the cells that were deleted by the normal x-wing, but it also deleted the 9 in r3c3.

But then I still used the x-wing 1 and xy-wing (1-56) to complete the puzzle.

Ted
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