## Help with very hard

Advanced methods and approaches for solving Sudoku puzzles

### Help with very hard

People from http://www.dailysudoku.co.uk say "SuDokus from the Daily SuDoku are always solvable using logic alone. You should never have to employ trial and error tactics"

But in 26-June sudoku I dont understand how to finish without trial and error, I've done easily with T&E, but as they say which is the next logic move here.

5 - - | 8 3 4 | - 7 1
8 - - | 2 1 7 |
1 - 7| 5 9 6 | 3 - -
- - - | 9 5 - |4 2 6
2 - - |6 8 - |7 - -
6 5 9 |4 7 2|8 1 3
9 - 5 |7 6 8 |1 - -
- - - |1 4 9 | - - 5
4 1 - | 3 2 5 |7 - -
moisty70

Posts: 3
Joined: 08 July 2005

### Re: Help with very hard

moisty70 wrote:which is the next logic move here.

You've almost certainly made a mistake somewhere as the puzzle you've posted here has no solution.

Edit: I found the puzzle you mentioned. Here is the starting grid:
Code: Select all
`...|..4|.718..|21.|.....7|.9.|3..-----------...|...|4262..|...|..7659|...|...-----------..5|.6.|1.....|.49|..541.|3..|...`

You will notice that you have the 7 in row 5 in the wrong spot. Maybe that's why you're having problems?
angusj

Posts: 306
Joined: 12 June 2005

You're rigth.
I copied the grid with at least that error, so, forget it.

Thanks.
moisty70

Posts: 3
Joined: 08 July 2005

i got exact the same solutions as you (have the 7 on the right place though) but still can't solve it. what's the next logical step?

thanks.
okami

Posts: 1
Joined: 12 July 2005

Look at block 7 and column 3 and where 6 can go. You're looking to eliminate candidates so you can fill (1,3)
Last edited by simes on Sun Dec 11, 2011 9:40 am, edited 1 time in total.
simes

Posts: 324
Joined: 11 March 2005
Location: UK

Ok thanks.

With sadman program now I'm sure is not necessary any trial and error strategy.

PD: Your clue was block not block 7, but not all has to be said
moisty70

Posts: 3
Joined: 08 July 2005