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Special
Posted: Tue Mar 27, 2007 10:04 pm
by Chris17
Hello!
Here is a puzzle with the given digits
{1,2,3} in block 1, block 6 and block 8,
{4,5,6} in block 2, block 4 and block 9 and
{7,8,9} in block 3, block 5, and block 7
in a way that each row and each column contain three digits as
well.
I found a lot of them. Does anyone know if there is a collection of
such puzzles somewhere?
Example(difficult one):
Code: Select all
1 . . | 4 . . | 7 . .
. 2 . | . 5 . | . 8 .
. . 3 | . . 6 | . . 9
---------------------
6 . . | 8 . . | 3 . .
. 5 . | . 7 . | . 1 .
. . 4 | . . 9 | . . 2
---------------------
9 . . | 2 . . | 5 . .
. 8 . | . 1 . | . 6 .
. . 7 | . . 3 | . . 4
100400700020050080003006009600800300050070010004009002900200500080010060007003004
Christoph
Re: Special
Posted: Wed Mar 28, 2007 10:50 am
by rep'nA
Chris17 wrote:Hello!
Here is a puzzle with the given digits
{1,2,3} in block 1, block 6 and block 8,
{4,5,6} in block 2, block 4 and block 9 and
{7,8,9} in block 3, block 5, and block 7
in a way that each row and each column contain three digits as
well.
I found a lot of them. Does anyone know if there is a collection of
such puzzles somewhere?
Example(difficult one):
Code: Select all
1 . . | 4 . . | 7 . .
. 2 . | . 5 . | . 8 .
. . 3 | . . 6 | . . 9
---------------------
6 . . | 8 . . | 3 . .
. 5 . | . 7 . | . 1 .
. . 4 | . . 9 | . . 2
---------------------
9 . . | 2 . . | 5 . .
. 8 . | . 1 . | . 6 .
. . 7 | . . 3 | . . 4
100400700020050080003006009600800300050070010004009002900200500080010060007003004
Christoph
A good place to start looking for puzzles of this shape might be
here.
As for your puzzle, this would be an excellent puzzle to teach somebody about naked pairs. I think I found 11 at the start. After these the puzzle isn't so bad. A swordfish on 5's eliminates 5 from r1c8 and r8c4. An xy-wing in r1c58, r9c8 implies r9c5<>9 and this solves the puzzle.
Alternatively, if one first eliminates [28] from r1c5 (using the naked pair in box 2), then an xy-chain
Code: Select all
.---------------.---------------.---------------.
| 1 69E 5689| 4 39D 28 | 7 235 356-|
| 47 2 69 | 1379 5 17 | 146 8 136 |
| 4578 47 3 | 17 28 6 | 124 245 9 |
:---------------+---------------+---------------:
| 6 179 129 | 8 24 1245| 3 4579 57 |
| 238 5 289 | 36 7 24 | 4689 1 68A|
| 378 137 4 | 1356 36C 9 | 68B 57 2 |
:---------------+---------------+---------------:
| 9 1346 16 | 2 468 478 | 5 37 1378|
| 2345 8 25 | 579 1 457 | 29 6 37 |
| 25 16 7 | 569 689 3 | 1289 29 4 |
'---------------'---------------'---------------'
eliminates 6 from r1c9. Locked candidates then removes the 6 from r2c3 and the puzzle is solved.
Nice puzzle Christoph.
Re: Special
Posted: Wed Mar 28, 2007 11:46 am
by Para
rep'nA wrote:
As for your puzzle, this would be an excellent puzzle to teach somebody about naked pairs. I think I found 11 at the start.
It is actually also a good puzzle to practice swordfish at after the naked pairs (actually 12, twice a naked pair in 6 boxes). You could find 6 swordfishes in this puzzle. Of course going to the xy-wing or xy-chain earlier shortens the path considerably.
greetings
Para
Re: Special
Posted: Wed Mar 28, 2007 12:28 pm
by rep'nA
Para wrote:
It is actually also a good puzzle to practice swordfish at after the naked pairs (actually 12, twice a naked pair in 6 boxes). You could find 6 swordfishes in this puzzle.
Wow! You are indeed correct. 6 swordfishes in a row (on 1,3,4,5,8,9). I don't recall seeing such a puzzle before. I've probably seen a puzzle with 6 swordfishes, but never in a row and all on different numbers.
rep'nA wrote:
Nice puzzle Christoph.
Multiply that compliment by 6.