Introduction

A* is a heuristic path searching graph algorithm. This means that given a weighed graph, it outputs the shortest path between two given nodes.

The algorithm is guaranteed to terminate for finite graphs with non-negative edge weights. Additionally, if you manage to ensure certain properties when designing your heuristic it will also always return an almost-optimal solution in a pretty efficient manner.

A heuristic is a method which is constructed to guide us to the optimal solution most of the time, which means we trade in some accuracy for a lot of speed (if the heuristic is well constructed).

In this article, we’ll go over:

• Some characteristics that we aim to have in our heuristic search algorithms in general.
• Show a logical progression from a greedy search to A*.
• Go through the aforementioned conditions which enable A* to solve our problem optimally and efficiently.

Table of Contents:

• Graph Search Characteristics
• Shortfalls of Other Algorithms
• The A* Algorithm in Java
• Cost Function - f(n)
• Move Function - g(n)
• Heuristic Function - h(n)
• Calculating A* Moves
• Pseudocode
• Implementation
• Creating a Good Heuristic Function
• Practical Terrain Example

#java #ai #artificial intelligence #graphs in java - a* algorithm #algorithm #graphs in java