The New Sudoku Players' Forum

[Goldplate]

Hello, Please could someone help me with this fiendish puzzle!

X X 8 | X 3 X | X X X
X 6 X | 9 X X | X 4 X
7 5 2 | 3 8 9 | 4 6 1
3 8 X | X X X | X X 5
X 1 9 | X 2 X | 8 7 3
X X X | X X 3 | X X 4
X 2 X | X X 1 | X 8 X
X X X | X 4 X | 1 X X

Many Thanks.
GoldPlate.

[wapati]

Perhaps we could if you gave us all nine lines?

[m_b_metcalf]

Hello, Please could someone help me with this fiendish puzzle!

X X 8 | X 3 X | X X X
X 6 X | 9 X X | X 4 X
7 5 2 | 3 8 9 | 4 6 1

There are two 3s and two 9s in the second box and two 4s in the third. This is not a standard sudoku puzzle.

Regards,

Mike Metcalf

[ArkieTech]

Goldplate said

Code: Select all

X X 8 | X 3 X | X X X
X 6 X | 9 X X | X 4 X
7 5 2 | 3 8 9 | 4 6 1
3 8 X | X X X | X X 5
X 1 9 | X 2 X | 8 7 3
X X X | X X 3 | X X 4
X 2 X | X X 1 | X 8 X
X X X | X 4 X | 1 X X


Block 2 has two 3'a and two 9's. That is diabolical

dan

[ronk]

Either r1, r2 or r3 is obviously missing.

The first step is to determine the missing row .... and then determine the missing clues in the missing row.

[Ruud]

Surprisingly, this puzzle can be solved with logic.

As Ron stated, one of rows 1, 2 and 3 is missing.

Row 3 is the only choice that would allow the original puzzle to be 180 degrees symmetrical:

Code: Select all

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

The original puzzle must have been something like this:

Code: Select all

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

For r3c1 we have the candidates 1,2,5,7
For r3c4 we have the candidates 1,2,4,5,6,7,8

When r3c1=1, r3c4=2,4,5,6,8
When r3c1=2, r3c4=1,4,5,6,7,8
When r3c1=5, r3c4=1,2,4,6,7,8
When r3c1=9, r3c4=1,2,4,5,6,7,8

All but one combination of these, when used as clues, lead to multiple solutions, the only valid combination is r3c1=5 & r3c4=7.

So this must be the original puzzle:

Code: Select all

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

Goldplate is stuck here:

Code: Select all

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

From the original puzzle, only singles will lead to this position, so we cannot be sure that the Goldplate has found the elimination moves.

Here is the first move:
Digit 4 is locked in box 1 + column 2. Eliminate 4 from r1c1 and r3c3.

Code: Select all

.------------------.------------------.------------------.
| 12-49!479   8    | 12456 3     2456 | 25679 1259  2679 |
| 12    6     137  | 9     15    258  | 2357  4     278  |
| 5    !349   13-4 | 7     16    2468 | 2369  1239  2689 |
:------------------+------------------+------------------:
| 7     5     2    | 3     8     9    | 4     6     1    |
| 3     8     46   | 146   167   467  | 29    29    5    |
| 46    1     9    | 456   2     456  | 8     7     3    |
:------------------+------------------+------------------:
| 1689  79    1567 | 2568  5679  3    | 25679 259   4    |
| 469   2     34567| 56    5679  1    | 35679 8     679  |
| 689   379   3567 | 2568  4     25678| 1     2359  2679 |
'------------------'------------------'------------------'

This is the second move:

Code: Select all

.------------------.------------------.------------------.
| 129   479   8    | 12456 3     2456 | 25679 1259  2679 |
| 12    6    *137  | 9     15    258  |*2357  4     278  |
| 5     349   1-3  | 7     16    2468 | 2-369 1239  2689 |
:------------------+------------------+------------------:
| 7     5     2    | 3     8     9    | 4     6     1    |
| 3     8     46   | 146   167   467  | 29    29    5    |
| 46    1     9    | 456   2     456  | 8     7     3    |
:------------------+------------------+------------------:
| 1689  79    1567 | 2568  5679  3    | 25679 259   4    |
| 469   2    *34567| 56    5679  1    |*35679 8     679  |
| 689   379  -3567 | 2568  4     2567 | 1     2359  2679 |
'------------------'------------------'------------------'

X-Wing for digit 3 in rows 2+8, columns 3+7. Eliminate 3 from r3c3, r3c7, r9c3.

From here, the puzzle can be solved with singles and locked candidates.

Figuring this out is in itself a more interesting puzzle

Ruud

[udosuk]

Here is the first move:
Digit 4 is locked in box 1 + column 2. Eliminate 4 from r1c1 and r3c3.

Code: Select all

.------------------.------------------.------------------.
| 12-49!479   8    | 12456 3     2456 | 25679 1259  2679 |
| 12    6     137  | 9     15    258  | 2357  4     278  |
| 5    !349   13-4 | 7     16    2468 | 2369  1239  2689 |
:------------------+------------------+------------------:
| 7     5     2    | 3     8     9    | 4     6     1    |
| 3     8     46   | 146   167   467  | 29    29    5    |
| 46    1     9    | 456   2     456  | 8     7     3    |
:------------------+------------------+------------------:
| 1689  79    1567 | 2568  5679  3    | 25679 259   4    |
| 469   2     34567| 56    5679  1    | 35679 8     679  |
| 689   379   3567 | 2568  4     25678| 1     2359  2679 |
'------------------'------------------'------------------'

This is the second move:

Code: Select all

.------------------.------------------.------------------.
| 129   479   8    | 12456 3     2456 | 25679 1259  2679 |
| 12    6    *137  | 9     15    258  |*2357  4     278  |
| 5     349   1-3  | 7     16    2468 | 2-369 1239  2689 |
:------------------+------------------+------------------:
| 7     5     2    | 3     8     9    | 4     6     1    |
| 3     8     46   | 146   167   467  | 29    29    5    |
| 46    1     9    | 456   2     456  | 8     7     3    |
:------------------+------------------+------------------:
| 1689  79    1567 | 2568  5679  3    | 25679 259   4    |
| 469   2    *34567| 56    5679  1    |*35679 8     679  |
| 689   379  -3567 | 2568  4     2567 | 1     2359  2679 |
'------------------'------------------'------------------'

X-Wing for digit 3 in rows 2+8, columns 3+7. Eliminate 3 from r3c3, r3c7, r9c3.

Ruud, not only were you smart in cracking this "puzzle", but you also invented a new technique that bewilds us totally!

After your "first move", somehow the 8 in r9c6 disappears, and we head straight to the "second move", an X-Wing for 3...

What should we name this move, "Houdini's (or should I say Ruudini's ) elimination"?

[Goldplate]

X X 8 | X 3 X | X X X
X 6 X | 9 X X | X 4 X
5 X X | 7 X X | X X X
7 5 2 | 3 8 9 | 4 6 1
3 8 X | X X X | X X 5
X 1 9 | X 2 X | 8 7 3
X X X | X X 3 | X X 4
X 2 X | X X 1 | X 8 X
X X X | X 4 X | 1 X X

[Ruud]

udosuk: You ARE a computer.

I skipped the Locked Candidates move in box 2 \ column 6 because it is not required to solve this puzzle. However, my computer solver wanted to do this step before the X-Wing. Forgot to return the candidate in the grid. Humans make such mistakes.

Goldplate: Thanks for the confirmation. The second half of my previous post shows you how to proceed. I'm just curious whether the original puzzle matches my assumption.

Ruud

[Goldplate]

Thanks for your explanation. I am so impressed you worked out the missing line.
I don't think you're Ruud- I think you are most polite!
regards
Goldplate

[udosuk]

Ruud, I had to pick on you out of something after you outsmarted all of the rest of us by working out all the combinations of r3c14... If I had been a computer I would have beaten you to work it out myself... I also wouldn't have spelt "bewilders" as "bewilds"...

[wapati]

Yep, Ruud just took it as a bigger puzzle and solved it.

Great job!


Udosuck, that was a compliment and a tease, I am certain.

Ruud is terse.

[JPF]

The work done by Ruud is impressive.
Congratulations !

Ruud, I had to pick on you out of something after you outsmarted all of the rest of us by working out all the combinations of r3c14...

It reminds me this thread

JPF