Need help to solve my own puzzle

Post the puzzle or solving technique that's causing you trouble and someone will help

Need help to solve my own puzzle

Postby Ocean » Mon Mar 20, 2006 1:28 pm

This is the C1-norm of one of the two known minimal sudokus with 35 clues:
Code: Select all
 *-----------*
 |123|45.|67.|
 |7..|3..|..4|
 |...|.6.|2..|
 |---+---+---|
 |312|...|78.|
 |87.|...|...|
 |..5|...|..2|
 |---+---+---|
 |68.|13.|4.9|
 |2.1|.4.|.6.|
 |.4.|.86|3..|
 *-----------*

I have not been able to solve it without using long forcing chains.
Maybe one of you experienced solvers could find the best/simplest solving strategy?
Ocean
 
Posts: 442
Joined: 29 August 2005

Postby vidarino » Mon Mar 20, 2006 1:55 pm

Good job on finding that one!

Basic steps should take you here;

Code: Select all
 1     2     3     |  4     5     9     |  6     7     8   
 7     569   68    |  3     12    128   |  59    159   4   
 49    59    48    |  78    6     178   |  2     1359  135 
-------------------+--------------------+--------------------
 3     1     2     |  56    9     4     |  7     8     56   
 8     7     46    |  256   12    123   |  59    3459  356 
 49    69    5     |  68    7     38    |  1     34    2   
-------------------+--------------------+--------------------
 6     8     7     |  1     3     25    |  4     25    9   
 2     3     1     |  9     4     57    |  8     6     57   
 5     4     9     |  27    8     6     |  3     12    17   


My solver suggests;
R2C8-1-R9C8-2-R9C4-7-R3C4=7=R3C6=1=[R2C56]-1-R2C8
-> R2C8 <> 1

The rest of the steps are pretty basic (the most complex being a hidden pair).

Vidar
vidarino
 
Posts: 295
Joined: 02 January 2006

Postby Carcul » Mon Mar 20, 2006 2:07 pm

Hi Ocean.

Ocean wrote:I have not been able to solve it without using long forcing chains.


That's strange, because this is a very easy puzzle:

Code: Select all
 *-----------------------------------------------------------*
 | 1     2     3     | 4     5     9     | 6     7     8     |
 | 7     569   68    | 3     12    128   | 59    159   4     |
 | 49    59    48    | 78    6     178   | 2     1359  135   |
 |-------------------+-------------------+-------------------|
 | 3     1     2     | 56    9     4     | 7     8     56    |
 | 8     7     46    | 256   12    123   | 59    3459  356   |
 | 49    69    5     | 68    7     38    | 1     34    2     |
 |-------------------+-------------------+-------------------|
 | 6     8     7     | 1     3     25    | 4     25    9     |
 | 2     3     1     | 9     4     57    | 8     6     57    |
 | 5     4     9     | 27    8     6     | 3     12    17    |
 *-----------------------------------------------------------*


[r2c3]-6-[r2c2|r2c7]-5,9-[r2c8]-1-[r9c8]-2-[r9c4]-7-[r3c4]-8-[r3c3]-4-[r5c3]-6-[r2c3],

which implies r2c3<>6 and that solve the puzzle.

Vidarino wrote:My solver suggests;


With all respect, it would be very nice if, at least from time to time, the progammers out there decide to try to solve a puzzle such as this one by hand, instead of just keep posting the output of the solvers (sometimes very long outputs).:D

Regards, Carcul
Carcul
 
Posts: 724
Joined: 04 November 2005

Postby vidarino » Mon Mar 20, 2006 2:25 pm

Carcul wrote:With all respect, it would be very nice if, at least from time to time, the progammers out there decide to try to solve a puzzle such as this one by hand, instead of just keep posting the output of the solvers (sometimes very long outputs).:D


Ah, you're just saying that because my chain was shorter than yours.

Just kidding.:)

I did actually solve it myself, using the Almost Unique Rectangle at R25C56, but the chain became rather long and unwieldy, and since Ocean asked for "the best/simplest solving strategy", I figured I should post my solver's chain instead, since it was much shorter.

When solving manually I have a real fetish for using AUR's, though. ;-)
vidarino
 
Posts: 295
Joined: 02 January 2006

Postby Ocean » Mon Mar 20, 2006 6:20 pm

Thank you both! As you pointed out, there is only one 'hard' step. Without a proper tool, I don't know how to quickly find the best logic there.

Thank you for the chains!
Ocean
 
Posts: 442
Joined: 29 August 2005

Postby tarek » Mon Mar 20, 2006 8:39 pm

I have to disagree on this Carcul....
I tried this by hand & oddly enough I spotted the Triple which is not needed & missed the double.......

The solver showed me the way, & I hope this is not long...
Code: Select all
*--------------------------------------------------------*
| 1     2     3    | 4     5     9    | 6     7     8    |
| 7     569   68   | 3    *12   *128  | 59    159   4    |
| 49    59    48   | 78    6    -178  | 2     1359  135  |
|------------------+------------------+------------------|
| 3     1     2    | 56    9     4    | 7     8     56   |
| 8     7     46   | 256  *12   *123  | 59    3459  356  |
| 49    69    5    | 68    7    ^38   | 1     34    2    |
|------------------+------------------+------------------|
| 6     8     7    | 1     3     25   | 4     25    9    |
| 2     3     1    | 9     4     57   | 8     6     57   |
| 5     4     9    | 27    8     6    | 3     12    17   |
*--------------------------------------------------------*
Candidates 38 form a Quantum cell as Candidates 12 in r2c5,r5c5,r2c6 & r5c6 form a unique quadrangle which leads to:
r3c6 Must only have 17 as valid Candidates (38 is a Naked Double in Column 6)
*--------------------------------------------------------*
| 1     2     3    | 4     5     9    | 6     7     8    |
| 7     569   68   | 3     12    128  | 59    159   4    |
| 49    59    48   | 78    6     17   | 2     1359  135  |
|------------------+------------------+------------------|
| 3     1     2    |*56    9     4    | 7     8    *56   |
| 8     7     46   |*256  ^12   ^123  | 59   -3459 *356  |
| 49    69    5    | 68    7     38   | 1     34    2    |
|------------------+------------------+------------------|
| 6     8     7    | 1     3     25   | 4     25    9    |
| 2     3     1    | 9     4     57   | 8     6     57   |
| 5     4     9    | 27    8     6    | 3     12    17   |
*--------------------------------------------------------*
Candidates 23 form a Quantum cell as Candidates 56 in r4c4,r4c9,r5c4 & r5c9 form a unique quadrangle which leads to:
r5c8 Must only have 459 as valid Candidates (123 is a Naked Triple in Row 5)
*--------------------------------------------------------*
| 1     2     3    | 4     5     9    | 6     7     8    |
| 7     569   68   | 3     12    128  | 59    159   4    |
| 49    59    48   | 78    6    *17   | 2     1359 -135  |
|------------------+------------------+------------------|
| 3     1     2    | 56    9     4    | 7     8     56   |
| 8     7     46   | 256   12    123  | 59    459   356  |
| 49    69    5    | 68    7     38   | 1     34    2    |
|------------------+------------------+------------------|
| 6     8     7    | 1     3     25   | 4     25    9    |
| 2     3     1    | 9     4    *57   | 8     6    ^57   |
| 5     4     9    | 27    8     6    | 3     12   ^17   |
*--------------------------------------------------------*
Eliminating 1 from r3c9(ALS-XZ A=157 in r8c6, r3c6 B=157 in r8c9, r9c9  x=5 z=1)

Tarek
Last edited by tarek on Mon Mar 20, 2006 9:30 pm, edited 2 times in total.
User avatar
tarek
 
Posts: 2631
Joined: 05 January 2006

Postby Havard » Mon Mar 20, 2006 8:40 pm

Here is another solution:
Code: Select all
*-----------------------------------------------------------*
 | 1     2     3     | 4     5     9     | 6     7     8     |
 | 7     569   68    | 3     12%   128%  | 59    159-  4     |
 | 49    59    48    | 78%   6     178   | 2     1359  135   |
 |-------------------+-------------------+-------------------|
 | 3     1     2     | 56    9     4     | 7     8     56    |
 | 8     7     46    | 256   12    123   | 59    3459  356   |
 | 49    69    5     | 68    7     38    | 1     34    2     |
 |-------------------+-------------------+-------------------|
 | 6     8     7     | 1     3     25    | 4     25    9     |
 | 2     3     1     | 9     4     57    | 8     6     57    |
 | 5     4     9     | 27#   8     6     | 3     12#   17    |
 *-----------------------------------------------------------*
ALS-XZ: x=7, z=1
Eliminating 1 from R2C8

solves the puzzle in a beautiful way!:)

havard
Havard
 
Posts: 377
Joined: 25 December 2005

Postby ravel » Tue Mar 21, 2006 12:18 am

Havard wrote:ALS-XZ: x=7, z=1

Thats what i want to spot in the puzzles since 2 weeks , but i failed again with this one - ok, keep on trying:)
ravel
 
Posts: 998
Joined: 21 February 2006

Postby QBasicMac » Tue Mar 21, 2006 1:29 am

Carcul wrote:With all respect, it would be very nice if, at least from time to time, the progammers out there decide to try to solve a puzzle such as this one by hand, instead of just keep posting the output of the solvers (sometimes very long outputs).:D


Get here easily enough:
Code: Select all
+-------------+--------------+---------------+
| 1   2    3  | 4    5   9   | 6   7     8   |
| 7   569  68 | 3    12  128 | 59  159   4   |
| 49  59   48 | 78   6   178 | 2   1359  135 |
+-------------+--------------+---------------+
| 3   1    2  | 56   9   4   | 7   8     56  |
| 8   7    46 | 256  12  123 | 59  3459  356 |
| 49  69   5  | 68   7   38  | 1   34    2   |
+-------------+--------------+---------------+
| 6   8    7  | 1    3   25  | 4   25    9   |
| 2   3    1  | 9    4   57  | 8   6     57  |
| 5   4    9  | 27   8   6   | 3   12    17  |
+-------------+--------------+---------------+


Then try r9c9=1. By singles, solves easily.

OK, try r9c9=7. By singles gives an invalid puzzle.

Hence, by hand, there is one solution. No solver required


Mac, programmer
QBasicMac
 
Posts: 441
Joined: 13 July 2005


Return to Help with puzzles and solving techniques