public BFSNode(Board nextBoard, Position blank_pos, BFSNode parent = null, Move move = null)
{
board = nextBoard;
this.blank_pos = blank_pos;
this.parent = parent;
this.move = move;
}
public BFSNode(BFSNode node)
{
board = node.board;
parent = node.parent;
blank_pos = node.blank_pos;
move = node.move;
}
public BFSNode()
{
board = new Board();
blank_pos = new Position();
parent = null;
move = new Move();
}
public bool Run(Board board, Position blank_pos, Board goal_board, ref List<Move> moves, int grid_size, ref int boards_searched, ref int open_list_size, ref long timer, ref long mem_used)
{
hf_ = new HelperFunctions();
if (hf_.CompareBoards(board, goal_board))
return true; //start board is goal
size_ = grid_size;
BFSNode root = new BFSNode(board, blank_pos);
BFSNode goal = new BFSNode();
HashSet<Board> searched_boards = new HashSet<Board>(new BoardEqualityComparer());
Queue<BFSNode> search = new Queue<BFSNode>();
search.Enqueue(root);
bool goal_reached = false;
System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
while(search.Count > 0 && !goal_reached)// && sw.ElapsedMilliseconds < 10000)
{
BFSNode node_to_expand = new BFSNode(search.Dequeue());
List<BFSNode> children = GetChildren(node_to_expand);
foreach(BFSNode child in children)
{
if (hf_.CompareBoards(child.board, searched_boards)) continue;
else if (child.board.Equals(goal_board)) { timer = sw.ElapsedMilliseconds; sw.Stop(); goal_reached = true; goal = child; }
else { search.Enqueue(child); searched_boards.Add(child.board); }
}
}
mem_used = GC.GetTotalMemory(false);
open_list_size = search.Count;
boards_searched = searched_boards.Count;
if (goal_reached) TraverseTree(ref moves, goal);
searched_boards.Clear();
search.Clear();
GC.Collect();
return goal_reached;
}
private List<BFSNode> GetChildren(BFSNode node_to_expand)
{
List<BFSNode> children = new List<BFSNode>();
foreach(Direction dir in directions_)
{
Position next_pos = hf_.GetCoordsFromDirection(node_to_expand.blank_pos, dir, size_);
Move move = new Move(next_pos, node_to_expand.blank_pos);
if (next_pos.x == node_to_expand.blank_pos.x && next_pos.y == node_to_expand.blank_pos.y) continue;
Board nextBoard = hf_.SimulateMove(node_to_expand.board, move);
BFSNode node = new BFSNode(nextBoard, next_pos, node_to_expand, move);
children.Add(node);
}
return children;
}
private void TraverseTree(ref List<Move> moves, BFSNode node)
{
moves.Add(node.move);
if (node.parent == null) return;
TraverseTree(ref moves, node.parent);
}
