Posts tagged Sudoku
Skyscraper 8×8
Jun 13th
I thought it would be fun to post an 8×8 Skyscraper puzzle today – larger than any previous ‘vanilla’ Skyscraper puzzles I’ve posted. As I’ve mentioned before I don’t believe that it’s possible to create an 8×8 Skyscraper puzzle without any givens within the grid, so this one has a slash of 4s across the diagonal to help you along the way and ensure a unique solution.
The rules are pretty simple: place 1 to 8 in each row and column whilst obeying the Skyscraper constraints, which specify how many numbers are ‘visible’ from each edge position whereby higher numbers obscure all lower numbers on that row/column. See earlier postings for more detailed instructions.
Good luck! 
SSSS: Skyscraper Shuriken Samurai Sudoku
Jun 5th
Skyscraper Shuriken Samurai Sudoku puzzle
I’m glad yesterday’s Shuriken Samurai went down well, so today I’ve upgraded it to a Skyscraper puzzle (following Christine’s request for more Skyscrapers!). This is, I think it’s fair to say, quite a bit harder than the basic Samurai yesterday was – but then any puzzle with a title this hard to say quickly really shouldn’t be able to be solved quickly either…
The rules are the same as yesterday (place 1-6 into each row, column and 2×3 box of the 13 underlying 6×6 Sudoku grids) but with the addition of Skyscraper constraints: place numbers so that the given number of digits can be ’seen’ from each external Skyscraper clue outside the grid. From the vantage point of each Skyscraper clue look along the adjacent row/column – with higher numbers obscuring all lower numbers (or those of the same value), the clue tells you how many numbers are visible. Check back to older puzzles I’ve posted for more detailed help.
Good luck! 
Shuriken Samurai Sudoku
Jun 4th
Here’s a fun little puzzle. A say ‘little’ because it revolves around 6×6 grids and some easy logic, although it actually involves 13 of them so it’s not exactly small either. But I think it looks quite fun – the X shape and the X of givens makes it look a Japanese Shuriken weapon (or perhaps that’s just me), but anyway here it is.
Simply place 1-6 into each row, column and bold-lined 2×3 box of each of the 13 underlying 6×6 Sudoku grids.
Good luck!
Double Samurai Star
Jun 3rd
Following Spittledung’s comment on the Samura-i puzzle about it being nearly a double samurai star / flower samurai, I thought it would be fun to try out what exactly that would really look like – and so here is the result!
All of the 11 possible 9×9 grids are present, and you must place 1-9 into each row, column and 3×3 box of each of these underlying grids.
Good luck!
Samurai Square 9-grid
Jun 2nd
I was thinking about the tight overlay of grids in the (improved) Samura-I puzzles, and wondered what it would be like if you made a 15×15 puzzle simply by overlaying 9 Sudoku grids at all possible offsets. The answer is attached. This is definitely rated easy – there are lots of possible eliminations at all stages, and you shouldn’t need pencilmarks to solve it.
Of course, this principle can be extended to any arbitrary size of puzzle, but I imagine it would get a bit tedious if it was much larger…
So – can you place 1 to 9 into each row, column and 3×3 bold-lined box of each of the 9 underlying Sudoku grids in this puzzle? You’ll need to solve all 9 grids simultaneously to reach the solution.
Good luck!
New improved Samura-i
May 30th
I decided that I didn’t like the inelegance of having 3 grids across the top and bottom but not 3 grids down the centre column in yesterday’s Samurai-I, so I’ve fixed this for today’s puzzle – it’s pretty much the same except that now there are 9 grids here, at all possible bold-line offsets.
So can you place 1 to 9 into each of the rows, columns and bold-lined 3×3 boxes of the 9 grids in this Samurai-I puzzle?
Good luck!
Samura-i
May 29th
Here’s a new layout of Samurai Sudoku – a Samura-i, or Samurai I if you prefer! There are 7 grids here – 3 each at the top and bottom and then one in the middle too. Place 1 to 9 into each row and column of these 7 grids, as well as 1 to 9 into each bold-lined 3×3 box.
Just to re-emphasise this, there are no grids with top-left corner at offset 3 across, 3 down or at 3 across, 9 down. There’s just the absolute centre grid and then the top row and bottom row of 3 grids each. (Maybe this is a bit confusing – feel free to comment if you think so!)
Good luck!
Toroidal Sudoku
May 28th
Sorry for the lower quantity of puzzles this past week – I’ve been working on completing a new book so I’ve had to focus on that instead, but next week I’ll hopefully get back up to my five-a-week average! I’m not feeling very inspired in terms of being too original right now so I thought I’d post a ‘regular’ 9×9 toroidal Sudoku, although this one is a little tricky through having only 14 given numbers to start from!
As my easy and hard puzzles attest, I’ve been doing a lot of work on really accurately rating Sudoku puzzles, something which I’ve only done in a more general way before on the basis of what logic was necessary to solve a puzzle – now I can do a much more detailed analysis of the number of simultaneous possible moves at any stage of solving the puzzle, what those moves are, and at what point in the solve process they’re required. I needed this new accuracy of rating for one of my new books that will be out later this year (actually pretty soon, at the start of July), shown left – Hard-as-Nails Sudoku. It has over 200 really-difficult puzzles – they start out tricky (more than 10 minutes to solve) and end up… well, even harder than the tough puzzle I posted last week! But at no point do they use any ‘unfair’ solving logic – they stick fair and square to logic that any solver could come up with themself, without help. And of course, no guessing is ever required.
Anyway, it doesn’t take a complex analysis to see that today’s toroidal is not going to be on the easy side, given the low number of givens and the fact that toroidal puzzles really do twist things up in a difficult kind of way – so good luck!
The opposite of difficult
May 27th
After last week’s very difficult Sudoku, I thought it would be fun to try the complete opposite – an extremely easy Sudoku! At all stages of this puzzle there are lots of possible places to go, which means that your target time to beat (if you care to try) is two and a half minutes.
If you’re interested, I solved it in 2:13 but that included correcting for a careless mistake where I added two ‘4’s to one of the boxes! I’m probably twice as slow as the world’s best solvers so whilst I’m certain some of them could manage it in under a minute, I think anyone who manages it in under 2 minutes should be very proud!
Of course, it’s just for fun and if you have an off day it could take you as long as 3 minutes…..
Good luck!
Samurai Star
May 23rd
You might be pleased to know that today’s puzzle is somewhat easier, despite being a lot bigger! It’s actually possible to comfortably solve this without making a single pencilmark, if you fancy an extra challenge.
It’s a Samurai Star / Flower Samurai puzzle. Just place 1 to 9 into each row, column and 3×3 box of the 5 underlying grids (there’s one in the centre too).
Good luck!
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