please give me some help for this x sudoku

For fans of Killer Sudoku, Samurai Sudoku and other variants

please give me some help for this x sudoku

[code]
5 8 9 l 3 2 4 l 1 6 7 l
6 3 7 l 1 8 5 l 4 9 2 l
1 2 4 l 7 9 6 l 5 8 3 l
_____________________
2 4 6 l 5 1 3 l 8 7 9 l
3 5 8 l 9 4 7 l 2 1 6 l
9 7 1 l 8 6 2 l 3 4 5 l
_____________________
4 1 3 l 6 5 9 l 7 2 8 l
8 9 5 l 2 7 1 l 6 3 4 l
7 6 2 l 4 6 8 l 9 5 1

in row 1 8-2-1-7 are givens r2 5-4-are givens, r3 no givens r4 1&9 R5 8, r6,5 r7, 4,3,9 r8 7,6 r9 6,8,5 As you can see I can solve, but not with the 1-9 on the diagonals, can someone help?
stevens

Posts: 9
Joined: 15 March 2006

Stevens for tips on posting look here.

It would help us to help you if you posted the original grid.

MCC
MCC

Posts: 1275
Joined: 08 June 2005

The starting grid for this puzzle is:
Code: Select all
` *-----------* |.8.|.2.|1.7| |...|..5|4..| |...|...|...| |---+---+---| |...|.1.|..9| |..8|...|...| |...|...|..5| |---+---+---| |4.3|..9|...| |...|.7.|6..| |.6.|..8|.5.| *-----------*`

Computer solvers will say it has "too many solutions to count" unless they can take account of the diagonal requirement.

Nonetheless, it is a difficult puzzle and I'm stuck! Stevens you will find it easier to start again. Consider the diagonals like any other row or column to make eliminations i.e. neither 3 nor 7 can go in any cell on the top right to bottom left diagonal and 5 cannot go in any cell on the top left to bottom right.

Also when you get to a point with only two candidate entries for a particular number on the diagonals - you can use this to eliminate at the intersecting cell. For example in this puzzle, you get to a point where 8 must be in either r4c4 or r7c7 - thus you can eliminate 8 at r4c7 and r7c4 (unless these cells are already filled).

See how you get on. I'll post where I got to later.

BTW What's the prize?
CathyW

Posts: 316
Joined: 20 June 2005

The 5 in r4c4 may have been your first incorrect placement.

If you want to see the correct solution, select the text below this line:

5 8 4|3 2 6|1 9 7
7 1 6|9 8 5|4 2 3
2 3 9|7 4 1|5 8 6
-----+-----+-----
6 5 2|8 1 4|3 7 9
9 7 8|5 6 3|2 4 1
3 4 1|2 9 7|8 6 5
-----+-----+-----
4 2 3|6 5 9|7 1 8
8 9 5|1 7 2|6 3 4
1 6 7|4 3 8|9 5 2

Ruud.
Ruud

Posts: 664
Joined: 28 October 2005

Ruud,
Your two diagonals don't each have all the digits 1-9. Here's what I get as the unique solution (select to view) ...

586 324 197
712 985 463
349 167 528

654 712 389
978 543 216
231 896 745

423 659 871
895 271 634
167 438 952

Solving was nothing fancy -- there were many cases of the type CathyW mentioned, where a digit could be eliminated from an off-diagonal cell due to the digit having only two candidate-placements on a diagonal. There were also some "diagonal-box" interactions, where a digit was locked in one of the diagonal segments in the central box (box5).
r.e.s.

Posts: 337
Joined: 31 August 2005

After a bit more studying - I have the same solution as res!
CathyW

Posts: 316
Joined: 20 June 2005

thank you all

for the help in solving these puzzles, I now have the right cords to go find the cache!!!!
stevens

Posts: 9
Joined: 15 March 2006

Do tell us what's in it!
CathyW

Posts: 316
Joined: 20 June 2005