December Beginners' Contest is over now. Passwords removed from booklets.

adityasaraf007 and khuski move to seasoners after Decembers contest.

I guess I'll had some of my own thoughts, as Fred did last month.

Classics: in general I quite like writing easy classics as you can really put a lot of thought into the design. With puzzle #1 I was hoping to get the digits 1-8, rather than 2-9 around the edge of the puzzle, but sometimes it doesn't quite work out like that. #2 featured some diagonal stripes - and this meant there were very few opportunities to put singles into the puzzle. Instead it was more profitable to solve by focussing on one or two digits at a time. This was supposed to be true of #3 as well, but it turned out even easier than that. I was astonished to see several sub-minute solves, with some as quick as 40 seconds! #4 was supposed to be a little trickier, and is based upon a favourite design of mine. I've used it in tests before, and as perhaps die hard fans of my blog will tell you, is (almost) the pattern I used for my first ever puzzle!

Variants: sometimes you just throw down a design and see where it gets you. With the added constraints that a variant can give, you often have a puzzle that needs very little tweaking. You can clearly see this is what I was after with the untouch puzzle. I was hoping not to need those digits in the 5th column, but didn't quite manage it. The killer was my favourite of the lot. Actually I was a little dopey when initially sketching out the cages and left blank spaces at R1C5, R5C1, R5C9 and R9C1. When I came to extend the cages that now contain those cells, I found that the puzzle still solved perfectly well. A pet hate of mine with killers is where you have to do too much adding up. I guess you have to do a bit to get yourself started here with the "cross" in the middle, but I much prefer to rely on logic that involves restricting a cage to a potential set of numbers and then using them as mini extra regions. So once you worked out how the L shaped 16 and 17 cages in the middle interacted, you were well on your way to solving. I suppose the outside was probably my least favourite of the set. I can't say I'm totally in love with this variant, but I tried to give a good clean solve and leave things well presented. The unfortunate thing with this sort of variant is that often you can miss the significance of one particular clue and be left scratching you head for a while until you come to re-examine it. Finally the anti-knight. I initially tried a design very similar to the untouch, but couldn't get it to work. In a fit of desperation (it was getting quite late that evening and i wanted to finish everything off), I had a look at Fred's completed grid from last month, permuted the digits and gave it a rotation, and then sketched out a striking design which I thought would solve uniquely. Without too much tweaking I got what I wanted. There are lots of subtle interactions with the antiknight logic for certain cells in the grid, and so if you knew what you were looking for the solve was fairly straightforward.

Anyhow, I hope everyone enjoyed the puzzles, congratulations to the winners, and my thanks to LMI for giving me the opportunity to showcase some of my puzzles :)

Tom

Thanks Tom for providing a nice set to solve. The detailed post about creating the grids is really interesting and useful too.

Anyway, the top 3 Beginners are zbych (Poland), DavidCollison (UK) and elena_tens (Greece). dp_94 had the best Indian performance among the Beginners.

Among Seasoners, no one got close to the fairly early "time to beat" set by jaku111 (Czech Republic). Timothy (France) and Gotroch (Czech Republic) are the "best of the rest" with 2nd and 3rd place respectively.

Congrats to all the winners, and thank you all for participating. :)

About Untouch Sudoku, can identical digits touch each other "diagonally"?
I can understand it's not allowed (by observing the Example), but I think some "beginner"s can't.

Yes, it's meant that they can't touch each other diagonally.

Well ... "diagonally" is the only way identical digits can touch each other in a Sudoku

[ Added the missing word in link for types. It was already present in pdf. ]

Heading of the contest page needs an update. It reads date in Dec.

Why it doesn't let me to print variants??

@TiiT, please check my messages

I would like to know if anyone has attempted correctly the 'Killer' sudoku in variants in LMI beginners' test, january. If yes, can anyone tell me the correct solution for the 'Killer' sudoku in variants. I have attempted it and think my answer is correct. But the server is showing the answer to be wrong. My answer is O-564782391 and P-327941865

Edited by huisouvik 2013-01-20 2:59 AM

@huisouvik, Please check your inbox for solution to killer.

hii is it valid to claim points for mistyping a number...when i first submitted the solution to answer for killer ,under time pressure ,in the second row of the answer solution i typed the wrong number as the first digit..i could not check again ..i had only 10 seconds remaining..after i completed i realised that i had lost 5 points for mistyping a single digit..not sure if it is valid to claim here...can the admin check my submission pls and see if it is a vaild claim....

Since we introduced the Instant Grading system with the lenient penalty, we decided that the only time we will remove the penalty is when an answer key is incomplete (has blank spaces). We have a system to notify us of these cases so the claiming button seemed redundant. Hence, we decided to remove it.

Obviously, we are aware that the rare case of someone making a slight mistake within time and then correcting it after time is possible, but we still don't think its a valid enough claim. If we award points there, its a disadvantage to people who are careful, submit just after time and don't have a typo just before time to show for it.

Not a problem.I know computing bonus would be a bit of a headache in the event that you decide to award points.. not that i would be getting much bonus anyway.It would not have felt right to me too if you had awarded for a mistake on my part.It is just that 6 points go down the drain because of a single typo that my heart forced me to claim.Thnks for looking into the claim......

Thanks Richard, the classics in particular were very elegant!

The January contest is now over. Passwords removed from booklets.

Congratulations to the players who took the top spots, both in Seasoners category (Jaku111, Timothy, Janoslaw) as well as in Beginners (zbych, elena_tens, affpuzz) category.

I am happy to see almost 270 participants!

I am also happy to see that a lot of Beginners were able to solve all Classics within the time limit and also that seven Beginners managed to solve all Variants in time. Well done!

When Deb asked me if I was willing to write a Beginners Sudoku Contest for LMI, I didn’t hesitate for a split second. It meant two challenges for me: First of all, I have never written a classic sudoku before. Second, writing interesting but EASY variants, sounds like a contradiction in itself to me.

Classics
I just started with the classics as I lack experience. It was fun to look for nice patterns of given digits with good solvable sudokus. I wanted the maximum number of given digits to be 27, use different kinds of symmetry and use some unusual patterns.
There is not much to say about it; no dirty tricks, no naked singles (I am not so good in spotting those, and that might be the reason I am not so fond of this technique, and thus don’t put it often in my own puzzles.) Only speed solving skills are required to tackle all four classics. And a lot of you managed to do so.

Variants
When I start making a sudoku variant, one of my goals is to reduce the number of clues to an absolute minimum. Especially for the puzzles I create for the puzzle portal in Germany I do this very often. The only exception to this rule is when symmetry is broken by removing a clue.

But for the puzzles that are part of a Beginners Contest, I had to let go this rule pretty soon; the puzzles would have become too hard that way. For example: the irregular didn’t have the 6 and 4 in the centre in the First version and the killer had the two cages of 6 combined to one of 12 in rows 2/3 and cages 10 and 9 combined to one of 19 in rows 3/4/5. Both puzzles were too hard, so I repaired the difficulty level by placing extra givens and by splitting the cages.

Some notes to some of the variants:
Untouch: the untouch rule is necessary only a few times. Mainly normal sudoku solving techniques are used.

XV: For this puzzle the 3 centre columns can be filled very quick. The blocks 1 and 9 provide a lot of information so you can proceed very fast after that. Especially when using the information where there is no X or V.

Killer: I am fond of larger cages and I love diagonal symmetry. I think eight cages of size two is pretty much the minimum for keeping it a quickly and smoothly solving puzzle. In my original puzzle there was a bigger role for the cage 28/7 in the center in combination with the cages 11/3 and 16/3 sticking out of the 3x3-block bottom right. Incredible to see that the fastest solvers tackled this one in around three-and-a-half minute!

It was my pleasure to create this Beginners Contest for you. I hope you all enjoyed it!

The 3rd Sudoku, XV has 2 good results, please check ! :)
326914578
497865123
158732649
814659237
735281496
962473851
689547312
243196785
571328964

Completely clueless about which Sudoku XV you are referring to. Please provide a link.

Pretty sure this is the XV Sudoku from the last WPF GP.

Frantz, all instances of X and V are given, so there can't be any digits adding to 10 or 5 anywhere in the grid except where the X's and V's are given. Because there are numerous places two adjacent digits add to 5 and 10 in your solution, where no X or V is given, you solution is not valid.

I hope this helps.