Thank you very much Deb. This is the step I missed -- the 178 not being allowed because of what it does with the {18} in the 2nd row and 2nd box. This single step allowed me to finish the rest of the puzzle in about 5 more minutes. I should not have missed this, and the puzzle is much more clever than I had originally credited it as being.

Great contest, thanks again.

hi deb :

i could solve all those variants sudokus (after taking a print out and juggling with it for more than a day) except that V and X type sudoku,, can u plz guide me through the steps ? and
i took 3 hours to solve killer sudoku,, is there any strategy to solve it quicker ? would u mind sharing the tricks ?

thanks in advance ..!

Zason, Glad that you liked the Product Frame Sudoku (and others too). In this puzzle one has to focus on 2 given products at the same time (unlike easy Product/Sum frame puzzles where one has work out single product / sum). The step you missed (and the 12/24 in box7 to begin with) were difficult steps, and this puzzle turned out to be the differentiator at the top, which is probably not ideal from a competition point of view.

The Killer Sudoku was difficult for beginners and little tricky for experienced solvers. It will be tough to list all the steps. I'll just post the beginning steps, and some tricks that beginners may not be aware of.

First the 30 at R6C3 and then the 23 at R5C2 gives you lot of pencil marks and 7 at R6C3



Now the maximum sum of R4C2 and R4C3 is 9 (4+5). so 26 at R3C2 will be (4+5)+(8+9)



So (1,2,3) at (R4C1,R5C1,R6C1)



Now, this is the step beginners are likely to miss. Lets assume R6C1=X (X can be 1 or 2 or 3), so where does X appear in Box7.
The only place for X in box7 is R9C2.



Since the sum at R8C1 is 20, X has to be 3.

Similar tricks can be be used in top part of the grid later (note that the grid is symmetric except 2 cages)

One more In-Out trick that can be useful later is the 45 at R3C4.
So if R3C4 is A, where does A appear in Box5. The only place is R4C6. Similarly for B at R7C6.


I'm not going to list all the steps, but look at 24 at R4C8, 11 at R8C6, 10 at R3C6.

Also, check that you can find the value of R3C1 and R9C4 with simple addition/subtraction.

So, challenge yourself again to solve it in 20 minutes :-)

The XV sudoku was little different because there were only few X / V marks on the grid. So box 7 and box 3 can be filled a lot easily. [ For example, R7C2 can be 7 or 8. But it can't be 7 because then R8C3 will be 2 (and 2 is already present in column 3). So R7C2=8 ]

After that all you need to remember is 2 digits can't be consecutive if their sum is 5 or 10 9 (since no more X or V are marked in the grid).
It is really an easy puzzle and I ask you to try it again. if you still face issues, post here.

Gowrishankar: For XV sudoku, to add to Deb's points, you must realize that the inverse rule is also true, i.e., if there is no V between two cells, the sum cannot be 5, and similarly for X. Here are a few (more than a few, actually) steps to get you started. The red cells are all obtained by XV rules and the blue cells based on normal sudoku rules.

After this I suggest you proceed on your own. For example, if you look at the left bottom corner cell, it cannot be a 9 (..as then it violates the rule for X) and so on. Do let us know if you are still stuck somewhere.

hi deb,

the first few steps which u explained to solve killer one was suffice,it eases to solve the rest ,especially i dint know the technique by solving it this way,,

i dint get wot u said below :
"After that all you need to remember is 2 digits can't be consecutive if their sum is 5 or 10 9 (since no more X or V are marked in the grid). "( copied from ur EARLIER reply to my query)
my point is : 2+3=5 and 2&3 are consecutive ryt ? y cant de go in cells marked with V,,

hope u don mind to rectify my mistake in query...!

hi rai:
i could solve those cells given for X and V da, however ur inverse law i m not getting .

"if there is no V between two cells, the sum cannot be 5, and similarly for X" how ?

u mean t say in a box if ter is no V between any two cells ,then those two cells wont be occupied by digits adding to 5? i dint get ,,,,dont mind to elaborate....

consecutive is a bad word to use. I meant adjacent cells.

My point was this (and Rakesh was explaining the same thing)
If there is no v between 2 adjacent cells, the sum of 2 digits can't be 5. So 2 and 3 can't be placed in adjacent cells if there is no V. Similarly, 1 and 4
Same rule applies for X as well.

now the point is clear to me ,, adjacent instead of consecutive,got it..,,!
thanks Deb:

in the page of ALL QUALIFIERS some are marked as registered and some are not. may i know what it means? i have registered in the website but it's not showing in the all qualifiers column.... may i know what that registered column is meant for?

hey can't we have the finals online?
is it necessary to be in Banglore for the finals??

The World Sudoku Championship is an offline event where every participant solves with paper-pencil. So, to get the best players, it is better to conduct the finals in a replicative format of the WSC. Hence, the need of an offline event.
Besides, there is no control over players in the online mode, and players 'may' use unfair means.

my point value for irregular sudoku is very low( took nearly 40 min to solve 59 pointer)...i think i am missing some basic steps used for solving it...could people let me know the methods they use??

why is it that some people are registered and some aren't ???
I do understand that some might have created an a/c on the site but it is necessary really to have one??

I too am facing the same dilemma!!!

First thing Ujjawal, are you one person or two??? when you say I too am facing the same dilemma, we assume its 2 people with same id...

Registered users are those who are registered at the LMI site... for this years ISC/IPC it doesnt make a difference if you are registered or not since a lot of people who qualified at various offline regional rounds need not be members at LMI.

You need to be registered only IF you decide to take part in any online test/competition being held at the LMI site.

Rishi

Thanks Rishi for explaining.

Just to repeat, the registered field does not have any weightage. It is just a tool for us to track.

If that matters, your name should be showing as registered now.
You registered today, there was no way we could show you as registered earlier.

i haven't yet recieved the verification email for IPC-2011. And in the qualifiers page, mine status too is showing unregistered. i have registered in this website 2 months ago.

again, Please send me the verification e-mail for IPC-2011.
Suryabhan Rathaur

email resent. check and reply.

ok got the mail.
thanx.