Need help with a Sudoku

[youtalkfunny]

12_ 346 57_
___ __5 _62
56_ 27_ __3

697 152 834
2_1 7__ 956
_53 _6_ 217

9_6 4_8 _25
__5 62_ ___
__2 597 641

Sorry I'm too ignorant to come up with a better way to display that.

I got that far, then stumped. I took a few guesses, and solved the puzzle. But you're not supposed to guess on these things.

Don't solve it for me, just tell me the next move, because I sure don't see it.

[Vavavoom]

I have been doing this for 25 mins now...can't find the next move either.....

[GAL]

I think you might have filled this in wrong> i've put in ever possible number and it always comes down to guessing.

No it's right.

what was the original? it ends up in no mans land in the end for me [img]/images/graemlins/confused.gif[/img]

[GAL]

the numbers are right but it does come down to guessing. Let the bottom left quadrant, top line middle number be 1, betwwen the 9 and 6.

[HesseJam]

The numbers are right and there is a unique solution. It seems to be a tough one. I didn't solve it but put it in my pocket sudoku which could solve it only by applying all its tricks. If you want to get the solution I'll post it in while...

[naphinfitos]

I entered it here: http://www.sudokusolver.co.uk/ and it said you have to guess.

[Duke]

[ QUOTE ]
12_ 346 57_
___ __5 _62
56_ 27_ __3

697 152 834
2_1 7__ 956
_53 _6_ 217

9_6 4_8 _25
__5 62_ ___
__2 597 641

Sorry I'm too ignorant to come up with a better way to display that.

I got that far, then stumped. I took a few guesses, and solved the puzzle. But you're not supposed to guess on these things.

Don't solve it for me, just tell me the next move, because I sure don't see it.

[/ QUOTE ]

In spots like this I play out options in my head until I run into a contradiction.

~D

[youtalkfunny]

Thanks for the effort, gang.

Here's the original:

USA Today Nov 23

[Cosimo]

Take these points under consideration:
__x ___ __h
aax qq_ s__
__x __q sh_

___ ___ ___
_B_ _F_ ___
b__ ___ ___

_C_ _E_ ___
cc_ ___ _gg
dd_ ___ ___

The g squares are leaf squares. Although choosing them first (randomly) can force the rest of the puzzle, they only interact with one other square each, and again that other square has 8 and 9 as options (the h squares here). Hence, ignore the g squares. Tricks like this help you narrow down where you need to look. Similarly, the h, s, and x squares don't affect anywhere else, ie they are forced by the q squares.

So, to conclude, the puzzle will have to be solved by the interactions among the bottom-left 6x6 subgrid (and maybe aa and qqq).

An out is suggested by the common two-value pairs in the leftmost two columns.

The a squares have to be 3 or 7. Note that there is no interaction with these two squares and anything else in the row; it is leaf-ish in that a forced restriction somewhere else is going to be easier to find. They are not true leaves because the 3 and 7 occur in different places elsewhere in the columns. Compare the gg and hh squares: the g squares are perfectly determined soley by the h squares. There's no internal restrictions or interactions there. Here, a interacts with b, c, and d squares.

Now look at the sets aa, Bb, Ccc, and dd. For one column, where there's a 7 in one of the c squares, there's a 3 in a, an 8 in d, and a 4 in b. This reduces to: in a column where there's a 7 in a c square, there's a 4 in the respective b square. I'll call this the c7b4 column restriction.

Now take BFEC. An 8 needs to be in either B or F, and a 3 in F or E, and a 1 in E or C. So BFEC is either 831x or x831. This 'forcing loop' puts restrictions on the Bb and Ccc squares.

Next step, in white: <font color="white">combine the forced loop with the c7b4 column restriction: if BFEC is 831x, then C has to be 7, which contradicts the column restriction. Hence BFEC is x831.</font>