The New Sudoku Players' Forum

[steve]

As a relative new comer to these amazing puzzles, I am fascinated by all of the arguments surrounding T&E. I have been so tempted but never tried it since I believe the author that it should not be necessary!!

I have no problem at all with the difficult ones but have so far been infuriatingly poor at the fiendish. Every time I reach the same point having exhausted the 'rules' I know.

Please could someone just give me a little nudge as to how to get say the next 2 numbers in this puzzle - it is number 95 from 18th March. Sorry if I have posted to the wrong forum but let me know if there is a better place I could have asked.

4 6 ? 1 ? 8 ? 2 ?
? ? ? 4 7 6 1 ? ?
? ? 1 9 ? 2 4 ? ?

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

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

[Pappocom]

Hello Steve. If you look in "The Times" forum under the "Sudoku: in papers and publications" section, you will find two Topics dealing with this puzzle. I think you should find the answer to all your questions there - but if you don't, please feel free to post again.

- Wayne

[Guest]

Hello Steve,

I don't know if this will help you, but below is the output generated by my Su Doku solver program (written in PureBasic) whilst it was solving puzzle 95. No trial and error was required.

Hopefully you will understand most of the output, but if you want any detailed explanations, please ask.
Notice that the (x,y) co-ordinates are relative to (0,0).
Also, the phrases 'Horizontal Bands' and 'Vertical Bands' are explained at www.thetimes.co.uk in the Su Doku article where the author talks about "slice and dice".

Code: Select all

Su Doku Logfile

Top-left and bottom-right cells are at (0,0) and (8,8)

Times #95 18-Mar-05  [62476]  Fiendish
SolvePuzzle(14)
Horizontal Bands
   (1,5) = 1
Vertical Bands
   (4,6) = 4
   (5,4) = 7
   (5,0) = 8
   (8,4) = 4
Nearly Complete Columns
   (5,8) = 1
Nearly Complete Blocks
   (3,0) = 1
Unique Fit
   (4,5) = 9
   (6,5) = 7
   (7,5) = 5
Horizontal Bands
   (2,5) = 4
Horizontal Bands
   (0,0) = 4
   (1,7) = 4
Single Row (boxes)
   (0,8) from 2579 to 579
   (2,8) from 25789 to 5789
   (6,8) from 2689 to 689
   (6,8) from 689 to 89
   (8,8) from 6789 to 789
Single Row (boxes)
   (0,7) from 1279 to 179
   (2,7) from 279 to 79
------
Count Fits (rows)
   (6,7) = 2
Count Fits (columns)
   (6,1) = 1
Single Box (columns)
   (7,3) from 369 to 39
   (7,4) from 3689 to 389
------
Count Fits (columns)
   (7,2) from 3678 to 67
   (7,7) from 1679 to 67
Count Fits (blocks)
   (7,6) = 1
Single Column (boxes)
   (8,0) from 3579 to 579
   (8,1) from 3589 to 589
   (8,2) from 35678 to 5678
------
Horizontal Bands
   (0,7) = 1
   (8,6) = 3
Nearly Complete Rows
   (0,6) = 2
   (1,6) = 8
Vertical Bands
   (2,1) = 8
Horizontal Bands
   (1,1) = 2
Count Fits (rows)
   (8,2) = 8
   (6,8) = 8
Count Fits (columns)
   (7,4) = 8
   (8,7) = 6
Count Fits (blocks)
   (7,2) = 6
   (8,8) = 9
Single Row (boxes)
   (2,0) from 3579 to 359
Single Column (boxes)
   (2,0) from 359 to 35
   (2,3) from 2379 to 237
   (2,4) from 2359 to 235
Single Row (boxes)
   (2,7) from 79 to 9
   (2,7) = 9
Single Box (rows)
   (7,1) from 39 to 3
   (7,1) = 3
Single Box (columns)
   (0,4) from 359 to 35
   (6,3) from 369 to 36
   (6,4) from 369 to 36
------
Nearly Complete Rows
   (8,1) = 5
   (0,1) = 9
   (7,7) = 7
Nearly Complete Columns
   (7,3) = 9
   (8,0) = 7
Nearly Complete Blocks
   (6,0) = 9
Unique Fit
   (1,3) = 7
Horizontal Bands
   (0,2) = 7
   (1,4) = 9
   (2,8) = 7
Nearly Complete Rows
   (4,2) = 3
   (1,2) = 5
Nearly Complete Columns
   (0,4) = 3
   (0,8) = 5
   (6,3) = 3
   (6,4) = 6
Nearly Complete Blocks
   (2,0) = 3
   (4,0) = 5
   (2,3) = 2
   (2,4) = 5
   (3,4) = 2
   (4,3) = 6
   (4,8) = 2
   (3,8) = 6
------
Check Solution

[possum]

Steve, su doku no 95 was very fiendish, and I have just been looking at a thread on the Times section of this forum that deals with that very puzzle. Looks like a few people were flummoxed by this one, but there are plenty of hints on that thread that should help you.

[gomo64]

Hello Steve.

I am working in this puzzle.

So I will be back.

Wish me Luck.

[Tony Williams]

Hello Steve.

I am working in this puzzle.

So I will be back.

Wish me Luck.

Hi,

Some comfort to know that this particular puzzle is very Fiendish, and I will give you part of my solver program output for this. The thing that makes it unusual is that the normal rules for a digit only once in a Row/Col/Sq actually yield no results at all !

The first 3 Iterations were spent applying rules that eliminated certain digit options for certain cells, and it is only on Iteration 4 that the 'normal' rules apply and it should solve from there

Cell Lebelling is 1 based , i.e (1,2) refers to r1c2

- - - - - - - - - - - - - - -
Iteration Number 1
- - - - - - - - - - - - - - -
Testing for Unique Placements
Test all Digits for unique to Row/Col/Sq
Testing for Pairs/Triplets [Rows]
Row 7 - Digit 2 is a Pair in the same Square ~ Columns = 1, 2
Digit 2 not allowed Cell( 9, 1)
Digit 2 not allowed Cell( 9, 3)
Row 8 - Digit 6 is a Pair in the same Square ~ Columns = 8, 9
Digit 6 not allowed Cell( 9, 9)
Digit 6 not allowed Cell( 9, 7)
Testing for Pairs/Triplets [Columns]
- - - - - - - - - - - - - - -
Iteration Number 2
- - - - - - - - - - - - - - -
Testing for Unique Placements
Test all Digits for unique to Row/Col/Sq
Testing for Pairs/Triplets [Rows]
Testing for Pairs/Triplets [Columns]
Col 7 - Digit 6 is a Pair in the same Square ~ Rows = 4, 5
Digit 6 not allowed Cell( 4, 8)
Digit 6 not allowed Cell( 5, 8)
- - - - - - - - - - - - - - -
Iteration Number 3
- - - - - - - - - - - - - - -
Testing for Unique Placements
Test all Digits for unique to Row/Col/Sq
Testing for Pairs/Triplets [Rows]
Testing for Pairs/Triplets [Columns]
Testing for x,y Pairs of Digits [Rows]
Testing for x,y Pairs of Digits [Columns]
Col 8 - Digits 6 & 7 are a Pair into Rows = 38
Digit 3 not allowed Cell( 3, 8)
Digit 8 not allowed Cell( 3, 8)
Digit 1 not allowed Cell( 8, 8)
Digit 9 not allowed Cell( 8, 8)
- - - - - - - - - - - - - - -
Iteration Number 4
- - - - - - - - - - - - - - -
Testing for Unique Placements
Test all Digits for unique to Row/Col/Sq
43 - Cell( 7, 8) = 1
44 - Digit 1 Only position in Row( 8) is Cell( 8, 1)
All Digit = 1 allocated
45 - Cell( 7, 9) = 3
46 - Digit 8 Only position in Row( 7) is Cell( 7, 2)

Hope this doesn't spoil your fun in doing this manually, but this one really is more Fiendish than most - a 'unique placment' is the term I use if that digit is the only available candidate for a cell. Up to this point there haven't been any, but there are form here on.

If you want the rest of the log file - then just post a Yes Please

Good luck.

[possum]

Look away now if you don't want a pretty heavy hint!

In column 8, rows 3 and 8 must be the 6 and 7. This was a clue given on the Times thread for this puzzle.