# Skyscraper Sudoku

It occurs to me that I didn’t get round to posting any ’straightforward’ Skyscraper Sudoku puzzles previously, so I thought I’d rectify that today. Attached is a regular 9×9 Sudoku with the addition of Skyscraper clues around the edge, and no other twists!

For the Skyscraper clues the numbers around the edge represent the number of digits visible from that point looking in along the row/column, where higher digits obscure all lower digits. So for example the solution to the clue ‘9′ would have to be 123456789, otherwise you couldn’t see all 9 digits; if the clue is ‘1′ then the first digit must be a 9, hiding all of the other digits. However the solution to the clue ‘8′ might be 134567829, where the ‘2′ is “hidden” behind the higher digits, or one of several other possibilities. For more examples and more detailed instructions click back to some of my older puzzle postings.

On a completely different topic, if you’ve had any trouble viewing the most recent few puzzles then I apologise – it turns out that some of them wouldn’t open in older versions of Adobe Acrobat Reader (version 7 wouldn’t open them, at any rate – the current version is 9.1). I changed the way I make PDFs a week ago, but I hope I’ve now fixed what I think was causing the problem! If today’s puzzle won’t open for you I’d be incredibly grateful if you could post a comment and tell me what PDF viewer you’re using and what error message you get!

Good luck with today’s puzzle!

Spittledungabout 12 years ago

I really enjoyed it, and would like to see more of these. I see this setup becoming a staple like Sudoku-X. Was this supposed to be a tough one? Because it took me a while and I even used a 5-link nice loop to figure out the 8s early on (an advanced Sudoku solving technique). When that happens I figure that I missed something obvious.

about 12 years ago

Yes, I think that’s a good point – it would make a good ’standard’ variant. (Perhaps with a few more givens to help make it easier.)

Well done on solving it! Just to answer your question, this puzzle required nothing more complex than hidden and naked singles and looking at region intersection inferences, in terms of the Sudoku logic – there were not even any naked or hidden pairs or higher, nor any more complex solving methods required. Perhaps there was a Skyscraper clue inference you missed somewhere along the way? However your method is great to hear about – it’s good that there are multiple ways to reach the solution!

Christineabout 12 years ago

There may be multiple ways to reach the solution but I haven’t found one yet!!! I’ve not got a mathematical background but perseverance and a lot of practice usually cracks most puzzles for me. However, these skyscrapers I find difficult! I do prefer a challenge to an easy puzzle though, so wouldn’t mind another one (maybe a little easier) to have a go at some time! I have come across these before and also think they could really catch on.

Andrewabout 12 years ago

I spent so long on this puzzle and I’m finally done with it. There’s something about the logic in it that I’m not grasping. I managed to solve it, but I had to guess once or twice and see where it lead and go from there. Is there something I’m missing? It’s probably all those complex terms and techniques you guys are talking about, I suppose. Where can I learn those? (5-link nice loop, hidden and naked singles, etc…)

about 12 years ago

I think it was the Skyscraper logic on this one that caught people out, because the actual Sudoku logic didn’t

requireany sort of particularly advanced logic (not even naked pairs or anything higher).So far as I’m concerned, in terms of complex logic I don’t intend to ever require any strategy which isn’t “intuitively obvious” to anyone who has solved a reasonable number of Sudoku. In other words, if you’re not likely to work it out on your own eventually then I think the strategy is too hard (at least for a general audience).

For definitions of strategies, take a look at Sudopedia. (NB I only use the ones near the top, and the solving technique called ’skyscraper’ has nothing to do with skyscraper sudoku/skyscraper puzzles!)