Posts tagged Sudoku
Jigsaw Sudoku
Oct 30th
I’m adding features back in to my new puzzle assistant front end code so today I thought I’d post the standard Jigsaw Sudoku puzzle that was my test subject – just fit 1-9 into each row, column and bold-lined shape.
Just a Sudoku
Oct 30th
I haven’t posted here for a while, but it doesn’t mean I haven’t been working on various puzzle projects. One of the things I have been doing is upgrading my puzzle assistant code to be easier to use and more integrated than ever before, and the first part of testing this is to make a plain and simple vanilla Sudoku. So here it is. It’s very easy.
Meanwhile, the recent US Sudoku Championship hit the news not just for its $25,000 (£15,000) prize pot but also because it seems one of the three advanced level finalists cheated to get to the final (and win $3,000 / £1,800), possibly because the organisers seem to have allowed people to have all sorts of electronic devices with them whilst solving. The cheques have been held whilst they work out what happened.
Solving Sudoku using Robots!
Sep 2nd
Sudoku Solver robot
Not a puzzle in itself, but I came across something related to Sudoku that’s so technically impressive that I just had to post about it.
There are plenty of online or interactive Sudoku solvers, and even some real-world ones which take the pages of a book, scan it in and then solve. SudokuGrab for iPod/iPhone is one popular example, whilst other people have used a combination of Lego and a webcam to scan in and solve entire books.
But how about this? A Sudoku solver robot which you can build yourself, and doesn’t even need a computer to drive it – it runs directly from a single Mindstorms Lego robotics kit. It’s unbelievable to watch it work, using a single point light sensor which the robot waves back and forth over the paper to build an image – there is no Lego webcam which can be integrated with the Mindstorms robotic kit. And then, as if it wasn’t already impressive enough, it uses a real pen to write in the solution.
It’s just amazing – take a look at the robot!
Stepping up – Three-away Sudoku!
Jul 21st
In a possibly inevitable next move (although in this case, I think, a probable conclusion to the theme rather than a stepping stone!) I thought I’d try out Three-away Sudoku, where black markers indicate all neighbouring squares with a difference of 3. With a 9×9 puzzle this still allows somewhat interesting 1-4-7, 2-5-8 and 3-6-9 chains to be used, although of course as you decrease the quantity of numbers that can fit in a chain so you start to lose the longer connected chains which I personally find so interesting.
Other than the three-away markers this is a regular 9×9 Sudoku puzzle, so just place 1 to 9 into each row, column and 3×3 box. Squares with a thick black bar between have a difference of 3 (e.g. 1&4), and those without a thick black bar between have a difference which is not 3.
An idea I have in mind to try next is to mix consecutive and two-away Sudoku in the same grid – I think any other combinations would be too confusing to play, although I suppose you could insert small numbers between squares to show selected differences which might make an interesting but possibly too mechanical variant. For me, I don’t want to have to stop and think about the rules I’m applying – in a good puzzle they should become intuitive really quickly (even if, in some cases, they are a little complex to learn they must become second nature for the puzzle to succeed – or so I find!).
Good luck! 
Two-away Jigsaw 8×8
Jul 20th
Continuing with Two-away puzzles, I thought today I’d post a somewhat smaller challenge – an 8×8 Jigsaw Sudoku version.
The rules are pretty much what you’d imagine: place 1 to 8 into each row, column and bold-lined jigsaw piece. Numbers with a grey bar between them must have a difference of 2 (e.g. 1&3) and numbers without a grey bar between must have a difference that’s not 2. (This is important to ensure a unique solution!)
Good luck!
Two-away Samurai Jigsaw
Jul 17th
Two-away Samurai Jigsaw puzzle
Here’s a puzzle for the weekend – it’s a 5-grid samurai sudoku where in the corner grids a couple of the 3×3 regions have had their outlines tweaked to turn them into jigsaw sudoku puzzles, with full 8-way symmetry. There are very few givens, which means you’ll need to take full advantage of the two-away markers that are also in the grid. The grey rectangles indicate all neighbouring squares where the difference is 2 (e.g. 1&3 or 6&8) – even without precise values they can also be useful for quickly indicating where a chain of squares are all odd or all even.
Good luck!
Two-away Samurai Star
Jul 16th
I made this puzzle yesterday but then went and forgot to post it (oops) so I’m making up for that now! It’s a Samurai Star with two-away markers, just as per the previous two puzzles I posted.
Place 1 to 9 into each of the rows, columns and 3×3 boxes of the 5 underlying Sudoku grids (including the one in the centre), whilst obeying the two-away grey bars. Squares with a grey bar between have a difference of 2 (e.g. 1&3 or 2&4), and those without a grey bar have a difference which is not 2.
There are only 4 givens to get you going, so good luck!
Easy Two-away Sudoku
Jul 9th
I thought that yesterday’s puzzle wasn’t the best example of a new variant, so here’s an easier Two-away Sudoku puzzle. It has a few more connected squares which means the odd/even nature of the puzzle comes through a bit more clearly – if you’re familiar with consecutive sudoku then it probably won’t take you very long to solve.
The rules are as yesterday: place 1 to 9 into each row, column and 3×3 box, and then wherever a grey bar separates two squares the difference must be 2 – they must be “two-away” – and conversely where there is no grey bar then the difference is not 2.
Good luck!
Two-away Sudoku
Jul 8th
I just noticed that Monday marked my 50th post to garethmoore.co.uk, so to celebrate I thought I’d try a (slightly) new variation today: Two-away Sudoku. As its appearance might suggest, it is a close relative of Consecutive Sudoku. In fact it’s pretty much the same, except that the shaded grey bars indicate that the difference between neighbouring squares is 2 (not 1, as in Consecutive Sudoku). As in Consecutive Sudoku, all grey bars are drawn – so if one is absent then the difference is not 2.
For example, if you see a grey bar next to a square with ‘1′ in it then the neighbouring square must be ‘3′. However if you have a square with ‘1′ in and there is no grey bar between it and a neighbouring square then that square cannot contain ‘3′. It’s pretty simple really.
So – just place 1 to 9 into each row, column and 3×3 box whilst obeying the grey two-away markers!
Good luck!
Wrap-around Consecutive Samurai Star
Jul 6th
Wrap-around Consecutive Samurai Star puzzle
I seem to be posting more infrequently than I intend, so I thought I’d compensate with a puzzle that would take somewhat longer to complete! Here, then, is a wrap-around consecutive samurai star. All squares with consecutive values (a difference of 1) are marked with white bars, including those at opposite ends of rows and columns – wherever there isn’t a bar, the values are not consecutive.
The Sudoku logic takes a few twists here and there – in fact at one point near the end you will need to spot a particularly nasty hidden set in one region.
To solve the puzzle place 1 to 9 into each row, column and 3×3 box of each of the underlying 5 Sudoku grids (including the one in the centre). You’re only given 4 givens to get going, but with the consecutive information that’s all you need to find a unique solution.
Good luck!
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