The New Sudoku Players' Forum

[donnawallach]

I probably should not have trying an evil puzzle considering that the hard ones are still too hard for me. I'm thinking that if you help me figure out this evil puzzle, it will make me better at Sudoku overall. I apoligize if this is not formated correctly, this is my first time posting a sudoku on this board.

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

My pencil markings as I decipher my scribbles are:

24567 23478 1 | 56 9 3456|23458 2357 234578
9 347 5 |1 2 8 |34 6 347
246 2348 2346| 7 46 346 |1 2359 234589
-------------------------------------------------------------------------------
2478 6 247 | 3 478 479 | 5 1 2789
3 1 247 | 295 4578 4579 | 289 279 6
278 5 9 | 26 678 1 | 238 4 2378
--------------------------------------------------------------------------------
1 3479 8 | 695 569 2 | 349 359 3459
257 279 27 | 4 3 579 | 6 8 1
456 349 346 | 8 1 59 | 7 2359 23459

Please help me figure out the solution to this puzzle. Thank you.

-Donna

[QBasicMac]

OK, I started with this

Code: Select all

+--------------------+-----------------+--------------------+
| 24678  23478  1    | 56   9     3456 | 2348  2357  234578 |
| 9      347    5    | 1    2     8    | 34    6     347    |
| 2468   2348   2346 | 7    456   3456 | 1     2359  234589 |
+--------------------+-----------------+--------------------+
| 2478   6      247  | 3    478   479  | 5     1     2789   |
| 3      1      247  | 259  4578  4579 | 289   279   6      |
| 278    5      9    | 26   678   1    | 238   4     2378   |
+--------------------+-----------------+--------------------+
| 1      3479   8    | 569  567   2    | 349   359   3459   |
| 257    279    27   | 4    3     579  | 6     8     1      |
| 2456   2349   2346 | 8    1     569  | 7     2359  23459  |
+--------------------+-----------------+--------------------+


Locked candidate 8 in box 4
Locked candidate 6 in box 7
Locked candidate 2 in box 9
Locked candidate 6 in col 6 Translation: Since all 6's in column 6 fall in box 2, then the cells in columns 4 and 5 cannot contain a 6. Remove 6 from r1c4 and r3c5. Now there is a single 6 at r1c4!
r1c4 = 5
r3c5 = 4

That gets us to here

Code: Select all

+------------------+---------------+-------------------+
| 2467  23478  1   | 5   9    36   | 2348  237   23478 |
| 9     347    5   | 1   2    8    | 34    6     347   |
| 26    238    236 | 7   4    36   | 1     2359  23589 |
+------------------+---------------+-------------------+
| 2478  6      247 | 3   78   479  | 5     1     2789  |
| 3     1      247 | 29  578  4579 | 289   279   6     |
| 278   5      9   | 26  678  1    | 238   4     2378  |
+------------------+---------------+-------------------+
| 1     3479   8   | 69  567  2    | 349   359   3459  |
| 257   279    27  | 4   3    579  | 6     8     1     |
| 456   349    346 | 8   1    59   | 7     2359  23459 |
+------------------+---------------+-------------------+


If you get this far, then look at 5 and 9 in row 3. They fall in two cells. Two candidates in two cells means all other candidates can be removed from those two cells. That is called "hidden pair 59 in row 3".
And there is a hidden pair 36 in col 3. See it?

After those eliminations, I only saw singles. Not what I would call "evil", just somewhere between medium and hard.

Mac

[QBasicMac]

P.S.
Your pencilmarks show this for r1c1: 24567

But there is a 5 in box 1

Therefore no other cell in box 1 can be 5.

Why don't you get a new pencilmark sheet and start over. Your original pencilmarks should be like mine: they are prior to any eliminations except those necessary because of placement of digits like 5.

Mac

[donnawallach]

Thank you for your help. I apologize for the error. We were able to solve the puzzle from your information. Could you explain how to format the puzzle on the board correctly?

-Donna

[Crazy Girl]

donna,

To see how we format our posts check out the link below,
http://forum.enjoysudoku.com/faq.php?mode=bbcode

Or at the top of QBasicMac's reply click Quote to see how he did his reply.

[dhoffman_98]

OK, I started with this

Code: Select all

+--------------------+-----------------+--------------------+
| 24678  23478  1    | 56   9     3456 | 2348  2357  234578 |
| 9      347    5    | 1    2     8    | 34    6     347    |
| 2468   2348   2346 | 7    456   3456 | 1     2359  234589 |
+--------------------+-----------------+--------------------+
| 2478   6      247  | 3    478   479  | 5     1     2789   |
| 3      1      247  | 259  4578  4579 | 289   279   6      |
| 278    5      9    | 26   678   1    | 238   4     2378   |
+--------------------+-----------------+--------------------+
| 1      3479   8    | 569  567   2    | 349   359   3459   |
| 257    279    27   | 4    3     579  | 6     8     1      |
| 2456   2349   2346 | 8    1     569  | 7     2359  23459  |
+--------------------+-----------------+--------------------+


Locked candidate 8 in box 4
Locked candidate 6 in box 7
Locked candidate 2 in box 9
Locked candidate 6 in col 6 Translation: Since all 6's in column 6 fall in box 2, then the cells in columns 4 and 5 cannot contain a 6. Remove 6 from r1c4 and r3c5. Now there is a single 6 at r1c4!
r1c4 = 5
r3c5 = 4

That gets us to here

Code: Select all

+------------------+---------------+-------------------+
| 2467  23478  1   | 5   9    36   | 2348  237   23478 |
| 9     347    5   | 1   2    8    | 34    6     347   |
| 26    238    236 | 7   4    36   | 1     2359  23589 |
+------------------+---------------+-------------------+
| 2478  6      247 | 3   78   479  | 5     1     2789  |
| 3     1      247 | 29  578  4579 | 289   279   6     |
| 278   5      9   | 26  678  1    | 238   4     2378  |
+------------------+---------------+-------------------+
| 1     3479   8   | 69  567  2    | 349   359   3459  |
| 257   279    27  | 4   3    579  | 6     8     1     |
| 456   349    346 | 8   1    59   | 7     2359  23459 |
+------------------+---------------+-------------------+


Mac,

I'm trying to follow along, because I'm learning about the logic that other people use. I'm curious about something in these instructions though. You gave an example of how you locked candidate 6 in box 2, and stated that "Since all 6's in column 6 fall in box 2, then the cells in columns 4 and 5 cannot contain a 6." I'm assuming that you meant the cells in columns 4 and 5 OF BOX 2 ONLY, but what about the 6 that shows up in r9c6? Doesn't that throw that theory away? Isn't it possible that the 6 in column 6 could have been in box 8 instead of box 2?

Just trying to understand.

And thanks for the tip on the hidden pairs. I had been waiting until the pairs were visibly apparent before removing clues from the same lines/boxes.

David

OOPS... OK, on second thought... If I follow your same logic path, the 6 that was in r9c6 was already removed if I locked the 6 in box 7, so I think I understand where you were coming from now. Thanks again.

[QBasicMac]

Reminds me of my days as a data processing manager. Staff would come in, completely stuck on some technical problem. They would tell it to me as I puffed on my pipe and looked intelligent. Suddenly they would exclaim "Oh! We see it now!" and thank me for my help and leadership and leave, spreading the word of what a guru I was.

I still wonder what they were talking about.

Mac

[CathyW]

It's amazing how often the solution becomes clearer just by explaining the problem to another person