The New Sudoku Players' Forum

[International_DBA]

https://andrews-sudoku.blogspot.com/201 ... tough.html

[Leren]

.3......2.....86.7..4..9......6..4..261.7......8......4...26.199..4..37.1..5.....

Not too tough. Apart from basics only a Skyscraper is required.

Code: Select all

*-----------------------------------------*
| 68 3  b79  | 1   456 a57  | 589 459 2   |
| 5  1   29  | 23  34   8   | 6   349 7   |
| 68 27  4   | 2-7 356  9   | 1   35  358 |
|------------+--------------+-------------|
| 7  9   5   | 6   13   23  | 4   28  18  |
| 2  6   1   | 8   7    4   | 59  359 35  |
| 3  4   8   | 9   15   25  | 7   26  16  |
|------------+--------------+-------------|
| 4  58 c37  |d37  2    6   | 58  1   9   |
| 9  25  26  | 4   8    1   | 3   7   56  |
| 1  78  367 | 5   9    3-7 | 2   68  4   |
*-----------------------------------------*

(7) r1c6 = r1c3 - r7c3 = (7) r7c4 => - 7 r3c4, r9c6; stte

Leren

[International_DBA]

Thank you for trying my puzzle.
No, it was not too difficult.
I will try to post a link to a harder one in a day or two.
It depends what my C program comes up with in the meantime.
My puzzle creation is fairly labour intensive right now.

[Mathimagics]

My puzzle creation is fairly labour intensive right now.

No need to apologise for that, software can paint a valid puzzle, but it usually needs an artist to produce something that is also elegant ...

[International_DBA]

Hello again.
I published this puzzle last night:
http://andrews-sudoku.blogspot.com/2019 ... lical.html

(Please feel free to delete the other topics I created and I will publish my links in this one from now on.)

[International_DBA]

I published this last night.
It is the hardest diabolical puzzle I have ever done (only 1 extreme puzzle is harder).
I would be really interested to hear what you think of it:
https://andrews-sudoku.blogspot.com/201 ... lical.html

[Leren]

......6.41..4..3...5..8.......8.34....1.7.52.6......18...7251...7.......3...4....

Certainly harder than a one stepper but solvable with fairly standard AIC's.

It has 13 one candidate elimination stte opportunities at 1 r1c4, 3 r1c5, 3 r3c3, 2 r3c4, 6 r3c6, 3 r6c2, 5 r6c4, 9 r6c5, 2 r6c6, 3 r8c4, 6 r8c5 & 1 r8c6. However, proving any of these in one move looks problematic.

I solved it in 6 non-basic moves. Two Skyscrapers, one W Wing plus two more interesting moves leading to BUG+1 at the end.

The most interesting move is this double kite loop (6) r8c5 = r2c5 - r3c6 = (6-3) r3c3 = r3c4 - r1c5 = (3) r8c5 loop => - 3 r1c4, - 6 r2c6, - 2479 r3c3, - 9 r8c5.

Code: Select all

*------------------------------------------------------------*
| 2789 2389  23789   | 125-3  f359   1279  | 6    5789 4     |
| 1    2689  26789   | 4      b569   279-6 | 3    5789 2579  |
| 2479 5    d36-2479 |e23      8    c2679  | 279  79   1     |
|--------------------+---------------------+-----------------|
| 2579 29    2579    | 8       1     3     | 4    679  679   |
| 489  489   1       | 69      7     469   | 5    2    3     |
| 6    349   3479    | 25      59    249   | 79   1    8     |
|--------------------+---------------------+-----------------|
| 489  4689  4689    | 7       2     5     | 1    3    69    |
| 259  7     259     | 13    ga36-9  1689  | 289  4    2569  |
| 3    1     2569    | 69      4     689   | 2789 5679 25679 |
*------------------------------------------------------------*

Later on after the W Wing I get (9=5) r6c5 - (5=2) r6c4 - (2=3) r3c4 - (3=6) r3c3 - r9c3 = (468-9) r7c123 = (9) r5c1 => - 9 r5c6, r6c23;

Code: Select all

*--------------------------------------------------*
| 27   2389  23789 | 125  359 1279 | 6   5789 4    |
| 1    2689  26789 | 4    569 279  | 3   5789 2579 |
| 4    5    d36    |c23   8   2679 | 279 79   1    |
|------------------+---------------+---------------|
| 257  29    2579  | 8    1   3    | 4   679  679  |
|g89   489   1     | 6    7   4-9  | 5   2    3    |
| 6    34-9  347-9 |b25  a59  249  | 79  1    8    |
|------------------+---------------+---------------|
|f89  f4689 f4689  | 7    2   5    | 1   3    69   |
| 25   7     259   | 13   36  168  | 289 4    2569 |
| 3    1    e256   | 9    4   68   | 278 567  2567 |
*--------------------------------------------------*

Basics then lead to the BUG+1 position => - 35 r1c5; stte

Code: Select all

*-------------------------------*
| 7 39 2  | 15 *9-35 19 | 6 8 4 |
| 1 69 8  | 4   69   7  | 3 5 2 |
| 4 5  36 | 23  8    26 | 9 7 1 |
|---------+-------------+-------|
| 5 2  7  | 8   1    3  | 4 9 6 |
| 9 8  1  | 6   7    4  | 5 2 3 |
| 6 34 34 | 25  59   29 | 7 1 8 |
|---------+-------------+-------|
| 8 46 46 | 7   2    5  | 1 3 9 |
| 2 7  9  | 13  36   16 | 8 4 5 |
| 3 1  5  | 9   4    8  | 2 6 7 |
*-------------------------------*

No doubt others will be able to find more elegant solutions.

Leren

[International_DBA]

Well done.
You are the 1st to solve this.
I usually post my puzzles to my "Sudoku Puzzles" Facebook group but none of my members have solved it there yet.

[Leren]

I put this puzzle into Hodoku and was pleased to find that their solution was almost identical to mine.

The only difference was that they didn't use the W Wing and used a variation of my 2nd AIC to remove four 9's and on to the BUG+1.

Leren

[International_DBA]

Some of the members in my group use Hodoku but I have not used it yet.
Here is another puzzle:
https://andrews-sudoku.blogspot.com/201 ... treme.html

[Leren]

8......4.1.2..98..6.......1....8..274.......3....76....3..5.........19...4.2.8.5.

That's your toughest puzzle yet. Took me 16 non basic moves to solve. Hodoku did better, with 10 non basic moves. I did solve though. Here is the solution.

Code: Select all

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

There are single candidate elimination single non basic move opportunities at 9 r1c2, 2 r1c9, 5 r3c2, 9 r3c8 & 9 r6c9, but chains to prove any of these would probably read like a few volumes of the human genome

I think I'll pass on detailing a solution. Leren

[International_DBA]

Well done. When I checked in my Facebook group, only one other person had solved it.

[International_DBA]

I published this just now:
https://andrews-sudoku.blogspot.com/201 ... treme.html

[Leren]

..35.8.2...1.62.5.5...1...3.....57.1.786..24..........48...6..9...........574.6..

Wow, a real tough one. Me, 20 non-basic moves, Hodoku a mere 17. But we did solve it. At least it solves with linear chains and URs. No nasty network forcing chains etc.

Code: Select all

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

Leren

[International_DBA]

Well done. That was the 2nd hardest puzzle I have ever published.