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I'm looking for pseudo-code examples of the A* pathfinding algorithm that actually works. I tried plenty of different ones where it's not really clear how to implement them at all times. Keep in mind that I'm a newbie, so if everything could be detailed, that'd be great.

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3 Answers 3

up vote 6 down vote accepted

I think the pseudocode in the Wikipedia article is sufficiently detailed. If you need more details and a working implementation then A* Pathfinding for Beginners is a good article. It has C++ sample code with comments.

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On my site I have an A* implementation I did in Actionscript based on this tutorial.

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It is really good! Although, I didn't know people still use ActionScript... –  jco Nov 8 '11 at 23:07
ActionScript is the most common language for Flash development by far. –  Gregory Avery-Weir Nov 9 '11 at 3:30

I implemented this one not too long ago and worked for me.

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That's exactly the one I looked into, but it doesn't work for me. Because when do I set a tile's "Next" step, and where it says "update the neighbor with the new, lower, g value" - what G value is it? I need something simpler. –  Mathias Lykkegaard Lorenzen Nov 6 '11 at 13:52
You calculate the G values as you generate each node, based on the cost to reach that node, and to travel between nodes. You already have that node's old G value from the first time you examined it. Now you have a new G value for the new route to that node. If the new route is quicker, you get to re-open the old node with the new and lower value of G. –  Kylotan Nov 6 '11 at 14:55

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