## An unsolved puzzle

Advanced methods and approaches for solving Sudoku puzzles

### An unsolved puzzle

Here is an unsolved puzzle.

4xxxxx xxx
5xx 4xx xxx
1xx 3xx 47x

956 738 xx4
2xx 549 736
734 1xx 895

x47 xx3 xx1
xxx x71 x43
3xx xx4 687

lthjason123

Posts: 4
Joined: 16 October 2005

### Re: An unsolved puzzle

lthjason123 wrote:Here is an unsolved puzzle.

How many of the 225 solutions do you want?
(ie: as you've typed it here, it's an invalid puzzle )
angusj

Posts: 306
Joined: 12 June 2005

I think this is a partly solved probem. Please post the original problem.
ramb

Posts: 4
Joined: 17 October 2005

### Re: An unsolved puzzle

angusj wrote:
" .......as you've typed it here, it's an invalid puzzle"

Hi Angusj. In the Simple Sudoku program, is there a way to know whether a puzzle is invalid before commencing to solve it?

Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

i am so sorry with that.
The diagram below is the origianl sudoku.

xxx xxx xxx
5xx 4xx xxx
1xx 3xx 47x

x56 xx8 xx4
2xx 5x9 xx6
7xx 1xx 89x

x47 xx3 xx1
xxx xx1 xx3
xxx xxx 68x
lthjason123

Posts: 4
Joined: 16 October 2005

Multiple solutions I'm afraid - although I could PM you ONE of them if you want!

stuartn
stuartn

Posts: 211
Joined: 18 June 2005

### Re: An unsolved puzzle

cecbevwr wrote:Hi Angusj. In the Simple Sudoku program, is there a way to know whether a puzzle is invalid before commencing to solve it?

Yes, in the statusbar Simple Sudoku will display a warning if a puzzle has multiple solutions.
For the puzzle above SS displays: "INVALID PUZZLE - 225 solutions".
angusj

Posts: 306
Joined: 12 June 2005

More numbers have/had to be given to give only 1 solution?
5udoku

Posts: 1
Joined: 28 August 2005

Heh - Easiest to "Solve" puzzle I ever saw.

Using normal techniques, one quickly reaches

Code: Select all
`Solution so far4-- --- ---5-- 4-- ---1-- 3-5 47-956 738 --42-- 549 736734 1-- 895-47 --3 --1--- -71 -433-- --4 687Pencilmarks So Far-         26789     2389      2689      12689     267       1235      1256      289      -         26789     2389      -         12689     267       123       126       289      -         2689      289       -         2689      -         -         -         289      -         -         -         -         -         -         12        12        -        -         18        18        -         -         -         -         -         -        -         -         -         -         26        26        -         -         -        68        -         -         2689      25689     -         259       25        -        68        29        259       68        -         -         259       -         -        -         129       1259      29        259       -         -         -         -        `

Then I couldn't see any more progress, so started guessing.

Starting from there, it seems that any guess leads to a "solution".

I guess we could suggest you get your puzzles from some other source.

Mac
QBasicMac

Posts: 441
Joined: 13 July 2005

### Re: An unsolved puzzle

angusj wrote:...in the statusbar Simple Sudoku will display a warning if a puzzle has multiple solutions.
For the puzzle above SS displays: "INVALID PUZZLE - 225 solutions".

Thank you angusj - your explanation is what I expected to be displayed after I have keyed in the puzzle but for some reason this warning does not appear. I've doubled checked and re-checked again the next day to ensure I've typed the puzzle correctly (which I'm sure I have) so there has to be some other reason why this warning does not appear.

I have downloaded the SS program and it works fine in all other aspects apart from the above mystery and it's driving me nuts trying to figure out what I've done wrong - particularly after my "X-Wing Confusion" blooper!

I enjoy these puzzles - although frustrating at times - but the help I get from you people makes it all worth while. Any thoughts as to what might be causing this problem would be appreciated.

Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

You're probably using an old version
Lardarse

Posts: 106
Joined: 01 July 2005

Cec, Instead of typing it in, try highlighting the grid above and copying it directly into SS using Edit & Paste.
emm

Posts: 987
Joined: 02 July 2005

Lardarse wrote:You're probably using an old version

I'm using version 4.1 which I believe is the latest but thanks anyway.

Em wrote:Cec, Instead of typing it in, try highlighting the grid above and copying it directly into SS using Edit & Paste.

Bravo Em - it takes a woman's touch. Your above suggestion immediately displayed in the status bar that this is an invalid puzzle with 225 solutions. Out of curiosity, after opening the SS program, I selected F2 then F3 to get a blank grid then again typed in this puzzle but still showing no warning that it's an invalid puzzle. It does permit progressive "solving" for about a dozen moves when a message appears in the status bar that there are no more hints available.

However, no problem now because I can use your "system".

Cec
Cec

Posts: 1039
Joined: 16 June 2005

[4,2,3,6,8,7,5,1,9]
[5,7,9,4,1,2,3,6,8]
[1,6,8,3,9,5,4,7,2]
[9,5,6,7,3,8,1,2,4]
[2,8,1,5,4,9,7,3,6]
[7,3,4,1,2,6,8,9,5]
[8,4,7,2,6,3,9,5,1]
[6,9,5,8,7,1,2,4,3]
[3,1,2,9,5,4,6,8,7]