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It's a great question Andy<br />
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It's so much easier to write an algorithm to <b>solve</b> Hashi than it is to create simply because not all combinations can be solved. &nbsp;This means any Hashi <b>generator</b> must by definition use recursion to check that a valid grid has been created and this in turn means as you increase the dimensions of the grid the odds on being unable to link all the islands in accordance with the rules becomes smaller and the validation process longer.<br />
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There are some good math texts on the theory but apart from very small scale grids I don't know of anything online. &nbsp;Solvers you'll find everywhere as it's a standard math/basic coding exercise for students.<br />
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I'd also be interested to see what gets found here.
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I agree, solving is often simpler. &nbsp;I could write something to solve bridges but it is a real pain to type in the grid contents.<br />
I did a suite of articles on EE about solving sudoku quite some time ago, starts here: &nbsp;<a href="https://www.experts-exchange.com/articles/3707/Sudoku-a-complete-MFC-application-Part-1.html" rel="ugc">https://www.experts-exchange.com/articles/3707/Sudoku-a-complete-MFC-application-Part-1.html</a>
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If you want pre-generated puzzles <a href="http://www.menneske.no/hashi/eng/" rel="ugc">http://www.menneske.no/hashi/eng/</a>
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Thanks. &nbsp;I've found numbers of online sites for either playing online or downloading the preprepared puzzles. &nbsp;(Search for Krazydad to find loads).<br />
The thesis looks interesting. &nbsp;I've had a quick scan through but the section on generating is pretty spartan. &nbsp;More or less what I had thought of myself - but there might be a much better way of doing it hence the question. &nbsp;<br />
I'll wait and see if anyone else knows some interesting ideas / code / algorithms about this.
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Thanks. &nbsp;Looks like there isn't a nice algorithm. &nbsp;(Makes me wonder then how one determines if easy/hard... to solve)
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Suspect that's based on a ratio of nodes with double bridges vs. those without - that's how I'd probably grade them anyway.
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A question about making puzzles for bridges (also known as Hashiwokakero or Hashi). &nbsp;<a href="https://en.wikipedia.org/wiki/Hashiwokakero" rel="ugc">https://en.wikipedia.org/wiki/Hashiwokakero</a><br />
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Is there an algorithm to generate a puzzle given the size of grid? &nbsp;Please provide algorithm or link to one if it exists.
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A question about making puzzles for bridges (also known as Hashiwokakero or Hashi).  https://en.wikipedia.org/wiki/Hashiwokakero

Is there an algorithm to generate a puzzle given the size of grid?  Please provide algorithm or link to one if it exists.

Algorithm to create a puzzle for the game bridges (NOT the card game bridge).

Game programming is the software development of video games. Game programming requires substantial skill in software engineering as well as specialization in simulation, computer graphics, artificial intelligence, physics, audio programming, and input. Like other software, game development programs are generated from source code to the actual program by a compiler. Source code can be developed with almost any text editor, but most professional game programmers use a full integrated development environment (IDE).

Game Programming

An algorithm is a self-contained step-by-step set of operations to be performed. Algorithms exist that perform calculation, data processing, and automated reasoning. Starting from an initial state and initial input (perhaps empty), the instructions describe a computation that, when executed, proceeds through a finite number of well-defined successive states, eventually producing "output" and terminating at a final ending state. The transition from one state to the next is not necessarily deterministic; some algorithms, known as randomized algorithms, incorporate random input.