advanced patterns in A* Algorithm Implementation in C# - Heuristic Function Miscalculating Path Cost
I'm confused about I'm currently implementing the A* algorithm in C# for a pathfinding solution in a grid-based game. However, I'm working with unexpected behavior where the algorithm sometimes chooses a non-optimal path. After debugging for a while, I suspect the heuristic function is miscalculating the estimated cost to reach the goal. Here's a snippet of my implementation: ```csharp public class Node { public int X { get; set; } public int Y { get; set; } public float GCost { get; set; } // Cost from start to this node public float HCost { get; set; } // Estimated cost to goal public float FCost => GCost + HCost; // Total cost } public float Heuristic(Node a, Node b) { // Currently using Manhattan distance for the heuristic return Math.Abs(a.X - b.X) + Math.Abs(a.Y - b.Y); } public List<Node> AStar(Node start, Node goal) { var openSet = new List<Node>(); var closedSet = new HashSet<Node>(); openSet.Add(start); while (openSet.Count > 0) { openSet.Sort((a, b) => a.FCost.CompareTo(b.FCost)); var currentNode = openSet[0]; openSet.Remove(currentNode); closedSet.Add(currentNode); if (currentNode == goal) { // Reconstruct path and return } foreach (var neighbor in GetNeighbors(currentNode)) { if (closedSet.Contains(neighbor)) continue; float tentativeGCost = currentNode.GCost + GetDistance(currentNode, neighbor); if (!openSet.Contains(neighbor)) { openSet.Add(neighbor); } else if (tentativeGCost >= neighbor.GCost) { continue; } neighbor.GCost = tentativeGCost; neighbor.HCost = Heuristic(neighbor, goal); } } return null; // No path found } ``` I've been testing the algorithm on a simple 5x5 grid, and it's supposed to navigate from the top left corner to the bottom right. However, when there are multiple paths, it seems to be favoring paths that are longer in terms of distance. For example, when there is a clear path directly down and to the right, it sometimes chooses a longer zigzag route instead. Could my heuristic function be the scenario? Is there something wrong with how I'm calculating the FCost? I've also considered that the sorting of the open set might not be optimal, but I don't see any major issues with that. Any insights on how to debug this further or suggestions for improving the heuristic would be greatly appreciated!