sudoki

[kwicky]

Although I manage to do the Times fiendish sudoki quite easily I am nearly always stumped on the harder versions of the Killer version. What are the techniques that will enable me to do so?

[Russ Bee]

As a starter, you need to think about the combinations that work in Kakuro, whilst seeing that some dashed regions cross multiple grids. It seems to wrk for me!

[JamesEverton]

The numbers 1-9 when added together equal 45. Where a region is contained wholly within a column/row/square you can deduct its total from 45 to deduce the combined values of the remaining squares. Where you know the combined value of 8 of the squares the remaining square is a gimme.

There are certain combinations that must always be true.

2 squares:
3 - 1,2
4 - 1,3
16 - 7,9
17 - 8,9

3 squares:
6 - 1,2,3
7 - 1, 2,4
23 - 6,8,9
24 - 7,8,9

etc etc. Even if you don't know which order within the numbered region that the digits must be you can use this knowledge to infer other values using the standard suduko row/column/region rules.

Those are some of the basics - you get the idea.

[kwicky]

Thanks for the replies. I was aware of JamesEverton methods but came to a brick wall soon after that. After giving it extra thought I believe I may have come to a complete solution although it involves a fair bit of work.
ie After initial work where a sufficient digits can be seen or calculated to fill out other rows, squares or colums with ALL the possible number combinations. If say 1 and 9 for example are the only numbers found then enter 2 to 8 in that box and so on for that portion. This will usually result in extra digits found. To do this an enlargement of the puzzle is usually necessary. This system does work although it seems cumbersome.