Nice and simple, but I’m a big fan of Amit Patel / Red Blob Games articles on the subject, and more. The interactive visualisations really drive the point home, and also tackle less usual stuff like hex grids and circular objects in dedicated articles.
Amit's articles are fantastic. I devoured them in my early gamedev days (late 90s / early 00s). I finally got to meet Amit at GDC in 2017, I hope I didn't go into fanboy mode too much! He's the nicest guy. Worth following on Twitter too: https://twitter.com/redblobgames
Oh, thanks for the twitter link! Followed. I also found his site in my early programming years (2000) but took many years before I finally actually implemented A* and found it’s actually not hard (at least not for a toy implementation).
Amit Patels site made A* finally click for me. I’ve implemented breadth first search before and it was a nice moment when I realised that Dijkstra’s is a minor change to BFS and A* is just a one line change (plus the heuristic function) to Dijkstas’s. Very well written with nice interactive illustrations.
Additional info (known to most, but might be useful for someone): A* is not at all specific to path finding; it's a general strategy for optimized search across a problem space.
If you want to understand A* , just watch this animation.
I had to do better than A* recently. Didn't have enough memory for all the data A* needs. Used "head for goal, hit wall, follow wall both ways until fail or can head for goal again". Examines fewer cells than A* .
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