A*(A-Star)算法帮助

好吧，这是我更新的代码。它没有减速，但没有出现任何路径。

public static IntPosition[] GetPath(BlockType[,] blocks, IntPosition start, IntPosition end, int threshhold)
    {
        List<Node> MapNodes = new List<Node>();
        MapNodes.Add(new Node() { Position = start });
        bool[,] explored = new bool[blocks.GetLength(0), blocks.GetLength(1)];
        explored[start.X, start.Y] = true;
        int? endNode = null;
        int index = 0;
        while (endNode == null && index < threshhold)
        {
            List<Node> addNodes = new List<Node>();

            foreach (Node n in MapNodes)
            {
                //left
                if (n.Position.X - 1 >= 0)
                    if (explored[n.Position.X - 1, n.Position.Y] == false)
                        if (blocks[n.Position.X - 1, n.Position.Y] == BlockType.Open)
                        {
                            int i = addNodes.Count;
                            addNodes.Add(new Node() { Position = new IntPosition(n.Position.X - 1, n.Position.Y), ParentNode = n });
                            explored[n.Position.X - 1, n.Position.Y] = true;
                            if (addNodes[i].Position == end)
                                endNode = i;
                        }
                //right
                if (n.Position.X + 1 <= blocks.GetLength(0) - 1)
                    if (explored[n.Position.X + 1, n.Position.Y] == false)
                        if (blocks[n.Position.X + 1, n.Position.Y] == BlockType.Open)
                        {
                            int i = addNodes.Count;
                            addNodes.Add(new Node() { Position = new IntPosition(n.Position.X + 1, n.Position.Y), ParentNode = n });
                            explored[n.Position.X + 1, n.Position.Y] = true;
                            if (addNodes[i].Position == end)
                                endNode = i;
                        }
                //up
                if (n.Position.Y - 1 >= 0)
                    if (explored[n.Position.X, n.Position.Y - 1] == false)
                        if (blocks[n.Position.X, n.Position.Y - 1] == BlockType.Open)
                        {
                            int i = addNodes.Count;
                            addNodes.Add(new Node() { Position = new IntPosition(n.Position.X, n.Position.Y - 1), ParentNode = n });
                            explored[n.Position.X, n.Position.Y - 1] = true;
                            if (addNodes[i].Position == end)
                                endNode = i;
                        }
                //down
                if (n.Position.Y + 1 <= blocks.GetLength(1))
                    if (explored[n.Position.X, n.Position.Y + 1] == false)
                        if (blocks[n.Position.X, n.Position.Y + 1] == BlockType.Open)
                        {
                            int i = addNodes.Count;
                            addNodes.Add(new Node() { Position = new IntPosition(n.Position.X, n.Position.Y + 1), ParentNode = n });
                            explored[n.Position.X, n.Position.Y + 1] = true;
                            if (addNodes[i].Position == end)
                                endNode = i;
                        }
            }
            MapNodes.AddRange(addNodes);
            index++;
        }
        if (endNode == null)
            return new IntPosition[] { };
        else
        {
            List<IntPosition> path = new List<IntPosition>();
            path.Add(end);
            Node CurrentNode = (MapNodes[(int)endNode].ParentNode);
            bool endReached = false;
            while (endReached == false)
            {
                path.Add(CurrentNode.Position);
                if (CurrentNode.Position == start)
                    endReached = true;
                else
                    CurrentNode = CurrentNode.ParentNode;
            }

            path.Reverse();
            return path.ToArray();
        }
    }

public class IntPosition
{
    public int X;
    public int Y;
    public IntPosition(int x, int y)
    {
        X = x;
        Y = y;
    }
    public IntPosition() { X = 0; Y = 0; }
    public override bool Equals(object obj)
    {
        return ((IntPosition)obj).X == X && ((IntPosition)obj).Y == Y;
    }
}