How to Implement a Priority Queue for A* Algorithm in Java without Using External Libraries?
I just started working with I'm migrating some code and I'm working on a project and hit a roadblock. I'm currently working on implementing the A* search algorithm for pathfinding in a grid-based game using Java. However, I'm facing challenges with efficiently managing the open set of nodes. I want to implement a priority queue from scratch to handle nodes based on their costs, but I'm uncertain about the best approach for maintaining the order of nodes as I add and remove them. I've attempted to create a simple array-based priority queue, but it becomes inefficient when I frequently need to dequeue the node with the lowest cost. My current implementation looks like this: ```java class Node { int x, y; double fCost; Node(int x, int y, double fCost) { this.x = x; this.y = y; this.fCost = fCost; } } class PriorityQueue { private List<Node> nodes = new ArrayList<>(); public void add(Node node) { nodes.add(node); } public Node remove() { if (nodes.isEmpty()) return null; Node minNode = nodes.get(0); for (Node node : nodes) { if (node.fCost < minNode.fCost) { minNode = node; } } nodes.remove(minNode); return minNode; } } ``` While this approach works, I noticed performance issues as the size of `nodes` grows. The `remove()` operation is O(n) because I need to iterate through the entire list to find the minimum. I know that using a heap structure (like a binary heap) would give me O(log n) for insertion and removal, but I want to stick to a simple structure for educational purposes. Is there a more efficient way to implement this while still keeping it straightforward? Additionally, how should I handle cases where two nodes have the same `fCost`? Any suggestions about balancing simplicity with efficiency would be greatly appreciated. Thanks in advance! The stack includes Java and several other technologies. I'm open to any suggestions. I'm using Java 3.10 in this project. What are your experiences with this?