Finally Stuck

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Finally Stuck

Postby jack107 » Sat Oct 31, 2015 11:45 am

Hello.

from a book with 150 Sudokus I could solve all but one ...

... in the Word document I have put the plain puzzle and the puzzle, when I got stuck.


Have I already made a mistake so far?

Or if not: whats the next possible step?


Thanks for your help!


Jack107
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Re: Finally Stuck

Postby JasonLion » Sat Oct 31, 2015 2:13 pm

MS Word isn't the best format for sharing. One of the two following formats is preferred, though photos are also alright.

Original puzzle
Code: Select all
. . 4 | . . . | . 8 7
. . . | . . 6 | . . 3
. . . | . 7 2 | 5 . .
------+-------+------
. . . | 5 . 3 | . . 9
2 . . | . . . | . . 4
6 . . | 7 . 1 | . . .
------+-------+------
. . 3 | 2 5 . | . . .
5 . . | 9 . . | . . .
7 8 . | . . . | 1 . .
..4....87.....6..3....725.....5.3..92.......46..7.1.....325....5..9.....78....1..

Stuck:
Code: Select all
. 2 4 | . . 5 | 6 8 7
. . . | . . 6 | . . 3
. . . | . 7 2 | 5 . 1
------+-------+------
. . 1 | 5 . 3 | . 6 9
2 . . | . . 9 | . 1 4
6 . . | 7 . 1 | . . .
------+-------+------
. 1 3 | 2 5 . | . . .
5 . . | 9 1 . | . . .
7 8 . | . . 4 | 1 . .
.24..5687.....6..3....725.1..15.3.692....9.146..7.1....1325....5..91....78...41..

The next step is fairly simple, where in row 7 can you put a 6?

But the puzzle does have a couple of middling steps and one rather more complex step after that.
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Re: Finally Stuck

Postby jack107 » Sat Oct 31, 2015 3:54 pm

Thanks Jason for the quick answer.


Actually i have made a mistake in the "Stuck-Version" of the puzzle.

I already got the easy 6 you mean, i only forgot to fill this one in (the rest is correct)


The problem is really this next "rather more complex step" you mentioned ...

can you give me some help here?


Thanks again

jack107


PS: next time I will use the formats your suggest for posting!
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Re: Finally Stuck

Postby JasonLion » Sun Nov 01, 2015 1:12 pm

Starting from placing the 6 in R7C9, you have:
Code: Select all
139   2     4     | 13    39    5     | 6     8     7   
189   579   5789  | 148   489   6     | 249   249   3   
389   369   689   | 348   7     2     | 5     49    1   
------------------+-------------------+------------------
48    47    1     | 5     248   3     | 278   6     9   
2     357   578   | 68    68    9     | 378   1     4   
6     3459  589   | 7     248   1     | 238   235   258 
------------------+-------------------+------------------
49    1     3     | 2     5     78    | 4789  479   6   
5     46    26    | 9     1     78    | 23478 2347  28   
7     8     269   | 36    36    4     | 1     2359  25   

In addition to several locked candidates, the next thing I notice is the naked pair on 68 in row 5. After the locked candidates are eliminated there is also a hidden pair in column 3.

I suggest you follow those steps through and and show us where you have gotten to before we give you the next hint.
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Re: Finally Stuck

Postby Leren » Mon Nov 02, 2015 2:51 am

The solution of this puzzle from your stuck position was simple but a bit tedious. The moves used by my solver were, in order :

6 pointing pairs, 1 locked pair in a row, 1 box/row intersection, 1 locked quad in a column, 1 hidden pair in a column, and 1 XY Wing.

As Jason said, see how far you can get before you ask for a further hint, or if you don't understand any of the move names I've mentioned, I can give you an example using your puzzle.

Well OK, here is the first of the moves I've mentioned.

Code: Select all
*--------------------------------------------------------------*
| 139   2     4      | 13    39    5      | 6     8     7      |
| 189   579   5789   | 148   489   6      | 249   249   3      |
| 389   69-3  689    | 348   7     2      | 5     49    1      |
|--------------------+--------------------+--------------------|
| 48    47    1      | 5     248   3      | 278   6     9      |
| 2    *357   578    | 68    68    9      | 378   1     4      |
| 6    *3459  589    | 7     248   1      | 238   235   258    |
|--------------------+--------------------+--------------------|
| 49    1     3      | 2     5     78     | 4789  479   6      |
| 5     46    26     | 9     1     78     | 23478 2347  28     |
| 7     8     269    | 36    36    4      | 1     2359  25     |
*--------------------------------------------------------------*

The above PM diagram is at your stuck position. Notice the 2 cells I've marked * in Rows 5 & 6 Column 2 (r56c2 for short). As these are the only 3's in Box 4, one of them must eventually be True in the solution.

This means that you can eliminate any other 3's in Column 2. There is one such 3, in Row 3, which I've marked as -3 in the PM. There are 5 more such moves in my solution. See if you can find them.

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Re: Finally Stuck

Postby jack107 » Mon Nov 02, 2015 9:47 am

Thank you very much for your answers!


As I can see there are lots of different technics necessary to solve a tougher puzzle ...

... and with your help I surely could learn them.


But I only wanted to find the solution for this 1 puzzle because it was this 1 out of 150 I could not solve on my own.

Actually I do not want to become a Sudoku buff. So I better stop it now.


Hope you understand,

thanks again for your efforts


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Re: Finally Stuck

Postby Leren » Mon Nov 02, 2015 10:30 am

Well, if you only want the solution to the puzzle here it is.

Code: Select all
*-----------------------------------*
| 3  2  4   | 1  9  5   | 6  8  7   |
| 1  5  7   | 4  8  6   | 9  2  3   |
| 8  6  9   | 3  7  2   | 5  4  1   |
|-----------+-----------+-----------|
| 4  7  1   | 5  2  3   | 8  6  9   |
| 2  3  5   | 8  6  9   | 7  1  4   |
| 6  9  8   | 7  4  1   | 3  5  2   |
|-----------+-----------+-----------|
| 9  1  3   | 2  5  8   | 4  7  6   |
| 5  4  6   | 9  1  7   | 2  3  8   |
| 7  8  2   | 6  3  4   | 1  9  5   |
*-----------------------------------*

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Re: Finally Stuck

Postby jack107 » Wed Nov 04, 2015 11:50 am

Leren wrote:Well, if you only want the solution to the puzzle here it is.


Thanks again, Leren!

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