The New Sudoku Players' Forum

[Guest]

Can anyone please help with the following


*3* **5 *62

**2 *6* *8*

*9* 2** **7

**9 176 5*8

*5* 9*8 *1*

**1 54* 6*9

9** 6** *4*

*6* *** 2**

7** 3** *96


Thanks
Also can anyone tell me some general methods to solving Hard Sudokus?
Thanks

[Guest]

I am just new here having read about this in the CM - Brisbane, Aust. I have downloaded the Sudoku trial and tried to dub your problem and it say's that this is not a valid puzzle which might explain why you are having problems.

[Animator]

First, look where the number 2 can go in box 7.

Now take a look at that column... you can exlucde the number from the other boxes, and this allows you to fill in another number..

[Guest]

Thanks for that clue Animator. I'm still stuck though, any more pointers?

[Animator]

No logical pointers...

In order to solve it you need to guess...

Did you copy it correctly? (and where did you get it?)

[ccx3]

Look at my post titled "The technique I use to solve the puzzles". Use it and there will be no guessing. Works every time for me (so far, anyway )

[Guest]

[quote="Del"]Can anyone please help with the following


*3* **5 *62

**2 *6* *8*

*9* 2** **7

**9 176 5*8

*5* 9*8 *1*

**1 54* 6*9

9** 6** *4*

*6* *** 2**

7** 3** *96


Thanks
Also can anyone tell me some general methods to solving Hard Sudokus?
Thanks[/quote]

[Animator]

Look at my post titled "The technique I use to solve the puzzles". Use it and there will be no guessing. Works every time for me (so far, anyway :D )

I seriously doubt that... the fact that the Sudoku program says it is an invalid puzzle is already a clue... and the fact that the solvers I tried cannot solve it without guessing... so either you are using a more complex ruleset then most of us, which is very unlikely.

[ccx3]

>> Animator said: I seriously doubt that...

I don't. My response was to the question at the end:

>>Also can anyone tell me some general methods to solving Hard Sudokus?

and I stand by my reply.

[Animator]

Ah, sorry for the confusion then

[Guest]

No problem, I should have made clear which bit I was replying to. "My bad" as we cool cats like to say.

[ccx3]

I keep forgetting to sign in before posting. The previous post was from ccx3.

[Guest]

Here's the solution:

437 895 162
512 764 983
698 213 457
349 176 528
256 938 714
871 542 639
985 627 341
163 489 275
724 351 896

I'll explain later.

[scrose]

I've been waiting so long for Lma03 to explain how (s)he reached his/her solution that I thought I would try and figure it out for myself.

I started by removing eight clues (r1c8, r2c5, r3c4, r4c4, r4c9, r6c9, r7c4, and r9c9) until I found a symmetrical grid. At this point I tried solving the grid and was able to refill four of cells I had removed (plus a fifth cell which corresponded to Animator's hint) before getting stuck. I quickly discovered that the 6 at r2c5 was necessary to find the remaining three clues I had removed. Using Lma03's solution, I put an 8 at r8c5 and suddenly I had a symmetrical grid with a unique solution.

I'm guessing that Del must have accidentally lost the clue at r8c5. I think this is how the original grid should have appeared.

Code: Select all

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

[dick]

Key blocks are (column 5, row 5) and (column 6 row 6). both of these blocks can use the number 2 or 3. If you put 2 in col 5, row 5 and 3 in col 6,row 6 you don't open any new oppertunities. however if you put a 3, in col 5, row 5 and a 2 in col 6, row 6 you should be able to solve the puzzle. Next step column 9, row 5 can only be a 4. You should be able to solve from here on.