Yajilin

Thought I'd start a new thread for this since it seems to have got mixed in with the Skyscraper topic. Lucky me has two weeks holiday from work over Easter so lots of extra time for puzzles!

Troy, thanks for the tips, these came in really useful - sometimes you just need the obvious stating like putting dots where squares are definitely part of the loop.

Gareth, it was great to have some easier puzzles to practise on - I have managed all three of the puzzles in issue 5 and really enjoyed them - so much so I have ordered Nikoli's sudoku and yajilin book from Amazon - I think Troy said there were a good range of sizes and difficulty in there. I have also managed the puzzles in issues 3 and 4, but not got anywhere with the ones in issues 1 and 2 yet. Will keep on trying. I never used to do loop puzzles apart from Slitherlink (can only do the easy ones of those) but since Sudoku Xtra I can now have a shot at masyu, nurikabe and now yajilin. Looking forward to trying out the suraromu next!

Well I've just finished making a 14x20 Yajilin for the next issue, so now you're able to do them perhaps that won't intimidate you too much. It's actually not particularly tricky - easier than some of the ones I've made before for sure! The givens are made up of a smiley face, an unhappy face and an indifferent face, which adds nothing to the puzzle solve but made it very frustrating to make so I think I will stick to simpler patterns in future.

I've also made a 14x20 Nurikabe consisting of givens in the shapes 'S', 'X' and a lone '6' which I am thinking of putting on the cover of issue 6 - but I will see how it fits when I come to lay it out.

The Yajilin book arrived from Amazon on Saturday and needless to say I've done a good few of the puzzles over the last couple of days and so now feel well equipped to tackle the one you are promising for issue 6!

Just in case anyone is interested the Nikoli series of books are really great for learning a new puzzle. This particular one - Yajilin and Sudoku contains 48 sudoku puzzles and 96 yajilin puzzles which is great as I wasn't bothered about the sudoku puzzles. The easy puzzles really are easy but I found that good for getting to grips with which cells could be blocked off and which couldn't possibly be, especially round the edges and corners of the puzzle. The medium ones are fairly easy too, but there is a great selection of hard ones including 10 x 18, 14 x 24 and 20 x 36 grids. I am fast becoming a convert. This and masyu are my favourite loop puzzles.

Christine, I'm glad you are enjoying the Yajilin puzzles! Once you get the feel, the puzzles aren't too difficult. I love puzzles that are somewhat challenging but are solvable in one sitting.

Gareth, I'm really looking forward to the 14 x 20 Yajilin and Nurikabe puzzles in issue six. Thanks. I'm still looking forward to the extra Yajilin in issue 5 as I ordered it as soon as it was available on Amazon (March 31 in the evening) and got the free shipping. Should only be a couple more days to arrive in Michigan.

Troy, I don't know whether you've seen, but nikoli have added two more sample puzzles to their Yajilin page both 20 x 36 classed as 'hard' - I haven't tried them yet, but a couple more for you to do whilst you wait for Sudoku Xtra 5 to arrive!!



Edited 1 time(s). Last edit at 04/06/2010 08:01PM by Christine.

Christine, I hadn't seen them yet. Many Thanks!!

The trouble with Nikoli's hard Yajilin is they're not actually very hard. Certainly easier than some of mine. I find their pencil puzzle books disappointingly easy - I don't have the Sterling one (Puzzlewright) talked about above so don't know what that's like, but usually their website puzzles are a lot trickier than those in their printed books, however, so I'm hoping those examples are misleading and once they start in the members' section that they'll ramp the difficulty up.

The ones I have so far from that series are Masyu & Sudoku, Fillomino & Sudoku and Slitherlink & Sudoku. I recommend them all - they're excellent, and I've surprised myself by doing quite a few of the (easy) Sudoku too.



Edited 2 time(s). Last edit at 04/07/2010 02:54AM by gareth.

I can only speak for myself because I am not a yajilin expert, but I am finding some of the difficult puzzles in the above book difficult! They start off easy enough bit once I get about two thirds of the loop done I am finding there are no clues left that I can use! I am having to avoid the tendency to trial and error the rest as it ends up in a mess! I know the clues must be in there somewhere and sometimes it helps just to put the puzzle down for a while and you spot something new when you get back! So I'm really enjoying this book, but I did find the easy and medium ones mostly very easy, so perhaps an expert might not find the hard ones difficult enough?

I have the masyu book in the same series - really enjoyed it - think it might be the fillominos next but had better wait a while as I need to get other things done as well as puzzles!!!!

No, that's fair enough. What I mean to say is that whereas on their website puzzles they seem to be continually innovating with the logic so that you get new things to discover, in their Yajilin books I've found that once you've cracked a certain percentage of the hard ones in one book you've essentially solved them all. So perhaps I shouldn't say that they're not tricky, but rather that they reach a certain point and then... well, just stop getting harder. In fact I think this is generally true of the printed Nikoli puzzles - they reach a certain level and then it's all about the grind, not the exploration. A bit like many Japanese computer games in fact, so perhaps that's something to do with their culture. Anyway, perhaps with a much more "serious" audience they do have some much trickier puzzles on their website - and, it must be said, some stunningly beautiful ones. They had an Akari (Light Up) in the shape of a bunch of flowers one day!

Having spent a fortnight doing loads of the puzzles in this book I know what you mean now Gareth! I keep coming across the same patterns in many of the puzzles. Having said that, it hasn't stopped me from getting to the end of some of the larger, harder puzzles and finding on closer inspection that I have two complete loops in there instead of one! Oops! I am definitely a convert to this puzzle now and am looking forward to doing the larger one of yours in Issue 6.

Nikoli have recently started putting Yajilin on their puzzle website. Interestingly I seem to be one of the top Yajilin solvers, which surprises me because none of the puzzles are particularly hard and yet the time spread is enormous (e.g. one today I did in about 5 minutes, but 99% of solvers took more than double that). They may be tougher than the ones in their books, but I think they still have a way to go to make them hard enough!

How did you find the one in Sudoku Xtra 6? It's not incredibly hard, but it has a few points where it's easy to get stuck for a little while.

Sounds as though you can compete with the best at Yajilin!

I really enjoyed the larger puzzle in Xtra6. I did find it tricky and didn't complete it in one go. If I get stuck oon a puzzle I often leave it and come back to it later with a fresh mind! It was the area just below the four '3s' (left of centre) which was causing the problem, and I eventually completed the loop using I would say about 90% logic and 10% trial and error, which I know isn't ideal but was the only way I could manage it!

This has become my firm favourite loop puzzle, closely followed by masyu.

I've been thinking (which should some day translate into actually doing...!!!) of making a book of loop puzzles - covering Yajilin, Masyu, Slitherlink and Suraromu. There are also a few other Japanese ones I like that could go in. But this is a way off, and I still have several other books I expected to have "in a week" a few months back... achum! The Consecutive Sudoku book is waiting on me doing better difficulty analysis on these, and the Skyscraper one is pending on me making some puzzles which don't have "all" clues round the edge. So I may do a Jigsaw Sudoku book first - these seem popular, based on Amazon sales figures - and if so I might include a range of puzzle sizes; or I guess I could do multiple books.

A book of loop puzzles sounds a great idea - I've nearly completed all the Yajilin and Masyu puzzles in the nikoli books so will be needing another source at some point! I enjoy slitherlink but apart from the really easy ones I seem to get stuck on these with no idea how to progress further! The Suraromu were fun so all in all a great idea for a Sudoku Xtra Special!

I think I must go against the grain when it comes to the most popular puzzle types as I don't do the 25 x 25 or 16 x 16 sudokus and don't include the jigsaws amongst my favourites either, but then I guess you have to go with what will sell the most! I am particularly enjoying the odd pair sudokus (but am not expecting a full book of those to appear!). I'm also looking forward to trying out the killer inequality puzzles you have included this month. I've never tried Akari so it will be interesting to see how I find those too. (Am a bit behind with the book this month due to the Yajilin but will soon catch up!!)

Gareth - just to say how much I enjoyed the extra large yajilin puzzle in issue 7 - it took me quite some time to complete but I managed to get there without any guesswork! It must be quite a work of art creating a puzzle which just reveals itself clue by clue without giving too much away in one go! Anyway, here's to the next one of those.....!

I'm really glad you enjoyed the Yajilin - that's the first time I've made one anywhere near that size!

I always try to put some interesting logic in the puzzles I make and the challenge is to keep that logic there by the time you're finished - because sometimes you end up having to compromise in order to give the puzzle a unique solution, so you add in extra clues which unfortunately make the tougher bits you started with easier than you'd hoped! I'm not really talking about Sudoku, but the loop puzzles (and Nurikabe) in terms of the ones I'm experienced with. With Yajilin in particular it's tricky to not end up "forcing" part of the loop somewhere else in the grid which then ends up short-circuiting some logic you put in elsewhere. As it turns out, one of the benefits of a bigger puzzle is that you have more flexibility to keep the bits you started out with. Having the symmetric arrow pattern (even though if you count you'll see I actually got one of the arrows one square out relative to its rotationally symmetric partner) made the puzzle quite constrained, and also led to some bits of logic that were repeated throughout - which is quite nice I think.

I'll tell you what though - I spent far longer checking (and doing a couple of minor fixes) and then re-checking and checking again than I did making the puzzle in the first place!



Edited 1 time(s). Last edit at 06/05/2010 04:59PM by gareth.