13. What is A*, what are its implementation details, and what are its advantages and drawbacks in regard to traversing graphs towards a target? Use PHP if necessary. Algorithm, Question, Explanation, Solution. At toptal-com .
By: Chrysanthus Date Published: 3 Feb 2026
A* is an algorithm for pathfinding that doesn’t attempt to find optimal solutions, but only tries to find solutions quickly and without wandering too much into unimportant parts of the graph.
It does this by employing a heuristic that approximates the distance of a node from the goal node. This is most trivially explained on a graph that represents a path mesh in space. If our goal is to find a path from point A to point B, we could set the heuristic to be the Euclidean distance from the queried point to point B, scaled by a chosen factor.
This heuristic is employed by adding it to our distance from the start point. Beyond that, the rest of the implementation is identical to Dijkstra.
The algorithm’s main advantage is the quick average runtime. The main disadvantage is the fact that it doesn’t find optimal solutions, but any solution that fits the heuristic.
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