## Determined to succeed !

Advanced methods and approaches for solving Sudoku puzzles

### Determined to succeed !

Alas I have not got v far - though I find this forum very useful for learing ....any tips appreciated - very hard from sudoku programme..

375 **6 **8
261 **3 ***
984 5** 6**

1** *59 3**
*** 134 ***
**3 67* **9

**2 *61 *85
*** 9** 2**
6** *** *7*
Arnie

Posts: 49
Joined: 19 May 2005

You really should take a look at column 7
Animator

Posts: 469
Joined: 08 April 2005

### process of elimination

I believe key is to identify cells that can have a choice between two numbers. Try one, see where it leads. If not to the solution, try the other only possible. This may leave having to pick another cell that also has only two possibilities and repeating the process.

I've solved this one and put solution at end.

How to get there?

r1c4 must be 2 or 4. I tried 2 and it led directly to solution.

To check method I then tried 4. Earlier clue to look at column 7 gives 9 must be in r7 or r9 so can't be in r1 or r2 in that column. This means r1c7 must now be 1 since I've put 4 in r1c4. This now means that r1c5 can be 2 or 9 but these both lead to error (overly constraining). So, r1c4 being 2 leads to r3c5 being 1 and r3c6 being 7 and r4c4 being 8 and away you go!

Solution is:

375 296 148
261 483 597
984 517 623

127 859 364
896 134 752
543 672 819

432 761 985
718 945 236
659 328 471 Regards, Neil.
Guest

Neil, thanks v much.... I follow up to where you say.."now means that r1c5 can be 2 or 9 but these both lead to error (overly constraining)."
I don't see the error (yet) ....but will keep looking....

Animator - I have studied column 7 and found the possibilities to be..
r1 1,4
r2 4,5,7
r5 5,7,8
r6 1,4,5,8
r7 4,9
r9 1,4,9

Does that mean column 7, rows 2,5 and 6 form a "triplet" containing only the numbers 5,7,8 ? If so, you can insert a 1 in r6c8.... does this take you any further? [/img][/quote]
Guest

Posts: 312
Joined: 25 November 2005

Yes... then you will find two other similar constructs...

I could give you the rows/column numbers if you really want...

neil, what you are suggesting is Trial and error, and as pointed out in another topic, that is really not needed.
Animator

Posts: 469
Joined: 08 April 2005

Thanks both of you - puzzle sorted !
Arnie

Posts: 49
Joined: 19 May 2005

### Re: process of elimination

neil wrote:Earlier clue to look at column 7 gives 9 must be in r7 or r9 so can't be in r1 or r2 in that column.

For the record: that was not the clue I was hitting on.

The clue was that there are three numbers in that column that can go in exactly three cells. This allowing you to remove those numbers as candidates for the others, leaving only one place for the number 1 in box 6.
Animator

Posts: 469
Joined: 08 April 2005