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A* Pathfinding for Beginners by Patrick Lester Updated July 18, 2005 ADVERTISEMENT This article has been translated into Albanian, Chinese, French, G erman, Portuguese, Russian, and Spanish. Other translations are welcome. See email address at the bottom of this article. The A* (pronounced A-star) algorithm can be complicated for beginners. While there are many articles on the web that explain A*, most are written for people who understand the basics already. This article is for the true beginner. This article does not try to be the definitive work on the subject. Instead it describes the fundamentals and prepares you to go out and read all of those other materials and understand what they are talking about. Links to some of the best are provided at the end of this article, under Further Reading. Finally, this article is not program-specific. You should be able to adapt whats here to any computer language. As you might expect, however, I have included a link to a sample program at the end of this article. The sample package contains two versions: one in C++ and one in Blitz Basic. It also contains executables if you just want to see A* in action. But we are getting ahead of ourselves. Lets start at the beginning ... Introduction: The Search Area Lets assume that we have someone who wants to get from point A to point B. Lets assume that a wall separates the two points. This is illustrated below, with green being the starting point A, and red being the ending point B, and the blue filled squares being the wall in between. [Figure 1] The first thing you should notice is that we have divided our search area into a square grid. Simplifying the search area, as we have done here, is the first step in pathfinding. This particular method reduces our search area to a simple two dimensional array. Each item in the array represents one of the squares on the grid,