Great test Rakesh!! All variants thoroughally enjoyable.

Just wondering, how did u guys approach the multitab sudoku?

Prime Exotica is over -
Congratulations to motris, David, deu and don3232.
motris finished well ahead of time getting huge bonus.
David played exceptionally well too.
deu and don3232 finished in just about the time.

Out of 186 players, 144 players got non-zero scores.
Out of 42 Indian players, the familiar names did better - Rishi, Rohan and Amit.

Congratulations to all, and thank you once again for your continued support and participation at LMI.

All participants whose number of points is not a prime number are disqualified !!!

Do you mean the "Top 9" are all disqualified !!!

Rakesh - well done. Excellent set of sudokus, fittingly rewarded by huge participation and good feedback.

Difficult to believe that it was your first attempt.

When will you update the Sudoku Ratings?

There were 13 (a prime number) "nick of time" finishers - those who sent in a correct answer in the last minute. And the winners here are:

1. 100:58 skywalker
2. 100:51 Nikola
3. 100:37 Kota

Very soon

Neeraj, DreamRose311, channa, bothrasumit: I had to edit your earlier posts because you had mentioned about the "no arrows" in Rossini on the forum. The grid was planned that way, but many solvers felt there was some mistake or missing arrows. Looking back, I think I should have put an explicit comment on the grid that "there are no arrows in this grid". That would have helped avoid the confusion.

Hi Rakesh,

That was very nice set of sudokus with new variants and it was really
enjoyable to deal with them. again to you, LMI and all
contributors for this event. And I'm not agree with you
for your last comment about Rossini. Because there was a clear
expression like "If there is no double arrow outside a
row/column, the nearest 3 digits CANNOT be in either
ascending or descending order." in the instructions and it
was really a good surprise to see that there were no double
arrows given for the grid . And I think there had been a smile
on the faces of solvers who dealt with it. So I think adding a
phrase like "there are no arrows in this grid" was no necessary
and spoil that effect. That's what I'm about that issue.

Regards,

Zafer

Thanks all for your feedback.

I am happy with the good participation level in this test (186 players from 35 countries), much more than I was expecting. Also, special thanks to many solvers who returned to LMI after some gap, notable among them being WaterlooMathie, drsteve and mackokajka.

Also, Fred did a very good job of testing the puzzles and eliminating some multiple solution cases.

I was worried about the timing for the test - whether it was correct. In the end, it seems that I got it right. Many top solvers were able to finish 12 puzzles and were on the verge of finishing the 13th, and except for motris and purifire (who had a very good chance to come first in this test), the others almost finished on time.

The median score in this test was 164, and average number of puzzles solved was 5.04.

Can any of you who solved this share your approach?

Lovely set of the puzzles. Great job, Rakesh! I prefer concept of DNA sudoku with a lot of clues. I took a wrong conclusion in numerologidoku grid and then I little lost a rhythm.
Congrats to all toppers!

Nikola

I can share my thoughts.... To begin with, I had a "cheat sheet" with all possible multiplication options with unique digits.... once that was ready I saw the 4 numbers at the vertices of the puzzle grid.... 5 at R1C1, 6 at R1C9, 9 at R9C1 and 4 at R9C9. This made me realise that the 4 and 5 form a pair and so do 6 and 9. any combination of multiplication options having 4 and 5 together and any combination having 6 and 9 together can be eliminated since they would go against normal sudoku rule. For example take the following option "7 x 94 = 658". take the pair of 4 and 5. since the number 5 is there in this option, it cannot be in the multitab in R1 or C1 and since 4 is also there in the option, it can neither be in R9 or C9. Hence this option can be eliminated. Similarly if any option had 6 and 9 that also got eliminated because of the same rule. Hence the list of options got significantly reduced to begin with. then from the rest we could eliminate more based on other numbers present in the grid. I am attaching the "cheat sheet" for better understanding.

I know its not a good method since we wont have any such sheets in a offline contest but since it was online and no mention of not using any "prepared" tools, i took the liberty of using this. That is precisely why I call it a "Cheat Sheet"

Rishi



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For the record, I had prepared a list as well. I didn't have Rishi's lovely 45, 69 insight. However, it didn't take too long to find the options which fitted. About the same length of time as it took for my printer to print out the test. There are 2 options missing from Rishi's list i.e 4x39=156 and 7x52=364. Just as well these weren't needed!

Enjoyed the contest very much. Thanks Rakesh and LMI. I also must confess to having a list of primes and the possible combinations of 4 digits totalling 17, which makes me a triple cheat!

David McNeill.

Thanks David, I too had the list of primes with me... I just didnt have the combinations of 17 ready

Rishi

Thx guys! I attempted it again with the list, and got it right away. I should try "cheat sheeting" next time.

Since we are discussing cheat sheets, another candidate was numerologidoku. An excel worksheet can easily save 3-4 minutes of calculation time - converting the names into clue numbers. Did anyone use this cheat sheet too?

this was the puzzle where i had got stuck at the end. got it wrong somewhere and after 7 min realised that i had goofed up . and then in our locality people are celebrating netaji's birhday and republic day . and so the local club turned on loudspeakers . the loudspeakers are still on and will be on till tomorrow.

Those who forgot to rate the puzzles or did not have time during the test can still rate the puzzles by visiting the test link.

I thought this would be a step too far - too much like using a calculator for the product sudoku. I went into the test with WPC rules in my head - anything written down was OK, but actually using a computer to speed up calculations would be frowned upon.

Wow. This forum went crazy in just the few short hours I was asleep. Now people are comparing (and posting) their cheat sheets to see who was better prepared? Seriously?

I personally disliked most of the puzzles that seemed to require extra/outside knowledge. Numerologidoku, for example, had no extra value to me for doing the addition. The puzzle itself solved fine once you had the sums, but I didn't feel doing the math added much value to the experience. In just the case of Kombinance, where the 9 groups should be obvious from the example (I saw no other way to finish that example than to make the connection of total # of groups), do I think - in accord with off-line tests - that "notes" were appropriate to bring in. But then my personal feelings aren't relevant so much as the author's goals and the test instructions themselves. There, no guidance was given - on the use of a calculator or a spreadsheet or printed notes. And the prime list link in the forum wasn't removed or turned away so as to say "do not bring such a thing into a test". So I think after the test it is worth a reevaluation of what the ground rules are for such a test and what should/should not be allowed. That, or simply choose puzzles that don't need extra information that doesn't add a lot of value. My favorite puzzles in this test, like the Rossini, simply solved as beautiful sudoku.

@ Rakesh
Hehe..dint realise that...this is first time i am attempting..thot prob with software or something...BTW, nice puzzleset...ruing the fact that i couldn't stumble upon this website long before....

How many ppl actually rote this test?? ..

Edited by channa 2011-01-25 10:02 PM

Thanks Rishi and David for sharing your approach.

Here's the approach which I had intended. Of course, there could be better and quicker approaches. But this is what I had thought of. Do let me know if any step is not clear.

Diagram A: One out of R9C4, R9C5 and R9C6 has to be a 1. And the first two cannot be a 1. So R9C6=1. Then R2C4, R1C8, and R5C9 also must be 1. Now in C1 and C5, there are two possibilities for 1 in R4 and R6. We must realize that R4C1 cannot be 1 as then we cannot get a three digit number after multiplication. So R6C1 and R4C5 are 1s.

Diagram B: Lets consider the last row. 2 must be one of the cells R9C4 or R9C5. This means R9C8 must be 6 (it cannot be 8). As we got 1 and 6 in the three digit number, it is not difficult to find the remaining numbers.

Diagram C: Now look at the last column. 5 goes into R6C9. Again, as we have got two numbers in the three digit number, the rest is easy to get.

Diagram D: R6C2=2. In column 1, 7 can be only in R4C1 (it cannot be in R3C1, because then multiplication will fail), which means R3C1=2, and the rest of column 1 falls through.After that, its normal sudoku rules and the top row also falls through.





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I think you meant "wrote". 186 people started the test and 144 submitted at least one correct answer.