really struggling...

Advanced methods and approaches for solving Sudoku puzzles

really struggling...

Postby piglet » Thu Jul 14, 2005 11:35 am

Someone has given me these. I have tried everything including x-wing and swordfish and I still can't crack them. What am I doing wrong?

8 9 5 0 7 3 0 4 1
6 1 2 0 0 4 0 0 0
3 4 7 0 1 0 0 0 0

0 0 9 8 3 0 4 0 0
0 2 0 0 4 0 0 8 0
0 0 0 0 6 5 1 0 0

0 0 0 0 9 0 7 0 4
0 0 0 3 0 0 0 0 9
9 5 0 4 2 7 3 0 8

and

0 9 0 0 5 3 4 2 0
0 1 3 4 9 2 8 0 0
0 4 0 0 6 7 0 3 9

0 0 1 5 2 4 0 0 0
9 2 0 3 1 8 0 0 4
0 5 0 9 7 6 3 1 2

1 0 9 2 4 5 7 6 0
0 0 5 7 3 0 2 0 0
0 7 0 6 8 0 0 0 0
piglet
 
Posts: 5
Joined: 12 July 2005

Postby Nick70 » Thu Jul 14, 2005 11:55 am

You are doing nothing wrong. Those two problems cannot be solved with techniques up to Swordfish.

Turbot Fish will allow you get farther, but it's still not enough. You'll need Double Forcing Chains, or Advanced Coloring.

The second one is quite interesting because it can be completely colored with a single color pair, placing 32 numbers out of 34 in a single step.
Nick70
 
Posts: 156
Joined: 16 June 2005

Postby piglet » Thu Jul 14, 2005 1:14 pm

Thank you. Were can I learn about these techniques? I've come across colouring before but I didn't understand it. Never heard of Turbot fish!
piglet
 
Posts: 5
Joined: 12 July 2005

Postby scrose » Thu Jul 14, 2005 2:57 pm

This thread in the programmers' forum contains some examples of advanced colouring. The Turbot fish is described in this thread.
scrose
 
Posts: 322
Joined: 31 May 2005


Return to Advanced solving techniques

cron