A* Algorithm

What is the A* Algorithm?

The A* algorithm is a popular pathfinding and graph traversal algorithm. It is widely used in robotics and games to find the shortest path between two points, especially when there are obstacles.

How Does It Work?

A* uses a best-first search and finds the least-cost path from a start node to a goal node. It uses a cost function:

• f(n) = g(n) + h(n)
  • g(n): The cost to reach node n from the start.
  • h(n): The estimated cost from node n to the goal (heuristic).

The algorithm explores paths that appear to be the most promising, based on the sum of the actual cost and the estimated cost.

Steps of the Algorithm

1. Add the start node to an open list.
2. Repeat:
   • Pick the node with the lowest f value from the open list.
   • If this node is the goal, reconstruct the path and finish.
   • Move the node to the closed list.
   • For each neighbor:
     • If it is not walkable or is in the closed list, skip it.
     • If it is not in the open list, add it and compute its f, g, and h values.
     • If it is already in the open list, check if this path to that node is better (lower g value). If so, update its parent and costs.

Why Use A*?

• Finds the shortest path efficiently.
• Can avoid obstacles.
• Works well in grid-based maps like the robot's arena.

Example

Suppose the robot needs to go from point A to point B in an arena with walls. The A* algorithm will calculate the best route, avoiding walls and minimizing the distance.

In the CollectorRobot Class

The CollectorRobot uses the A* algorithm to plan its movement in the arena, ensuring it can reach waste items or the sorter robot efficiently while avoiding obstacles.

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For more details, see this GeeksforGeeks article on A*.