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()
{
board = new Board();
blank_pos = new Position();
parent = null;
move = new Move();
}
public BFSNode(BFSNode node)
{
board = node.board;
parent = node.parent;
blank_pos = node.blank_pos;
move = node.move;
}
public AStarNode(Board board, AStarNode parent, Position blank, Move move)
{
parent_ = parent;
board_ = board;
blank_pos_ = blank;
move_ = move;
}
public AStarNode()
{
parent_ = null;
board_ = new Board();
blank_pos_ = new Position();
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;
}
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 memory_used)
{
hf_ = new HelperFunctions();
if (hf_.CompareBoards(board, goal_board))
return true;
size_ = grid_size;
AStarNode root = new AStarNode(board, null, blank_pos, null);
AStarNode goal = new AStarNode(goal_board, null, null, null);
PriorityQueue open_q = new PriorityQueue();
HashSet<AStarNode> open_d = new HashSet<AStarNode>();
HashSet<AStarNode> closed_list = new HashSet<AStarNode>();
open_q.Add(root);
open_d.Add(root);
bool goal_found = false;
System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
while(open_q.Size() > 0 && !goal_found) // && sw.ElapsedMilliseconds < 10000)
{
AStarNode next_node = open_q.GetNext();
open_d.Remove(next_node);
if (next_node.board_.Equals(goal.board_))
{
timer = sw.ElapsedMilliseconds;
sw.Stop();
goal_found = true;
goal = next_node;
continue;
}
List<AStarNode> successors = GetChildren(next_node);
foreach(AStarNode successor in successors)
{
if (hf_.CompareBoards(successor, closed_list))
continue;
successor.g = next_node.g + 1;
if (hf_.CompareBoards(successor, open_d))
continue;
successor.h = ManhattanDistance(successor.board_);
successor.f = successor.g + successor.h;
open_q.Add(successor);
open_d.Add(successor);
}
closed_list.Add(next_node);
}
memory_used = GC.GetTotalMemory(false);
open_list_size = open_q.Size();
boards_searched = closed_list.Count;
if(goal_found) TraverseTree(ref moves, goal);
closed_list.Clear();
open_d.Clear();
open_q.Clear();
GC.Collect();
return goal_found;
}
private float ManhattanDistance(Board other)
{
int manhattanDistanceSum = 0;
for(int i = 0; i < size_; i++)
{
for(int j = 0; j < size_; j++)
{
int value = other.board[i][j];
if(value != 0) //don't run MD for 0
{
int target_x = (value - 1) / size_;
int target_y = (value - 1) % size_;
int dx = i - target_x;
int dy = j - target_y;
manhattanDistanceSum += Math.Abs(dx) + Math.Abs(dy);
}
}
}
return manhattanDistanceSum;
}
public void Build()
{
Initialise();
//generate goal state
Board board_state = new Board();
Position blank_pos;
int counter = 0;
for(int i = 0; i < 4; i++)
{
List<int> temp = new List<int>();
for(int j = 0; j < 4; j++)
{
counter++;
if (counter == 16)
{
counter = 0;
blank_pos = new Position(3, 3);
}
temp.Add(counter);
}
board_state.board.Add(temp);
}
//run BFS in reverse from goal state to generate pattern database
//Create Hashset for searched boards
//Create FIFO Queue for successor nodes
//While successor nodes available
//Get next node to expand, NEXT
//Generate its children
//For each child
//if it has been searched already, discard
//else
//add child board to queue
//Find out which pattern was affected by change from NEXT to child
//create a new PatternNode for that pattern only
//set new PatternNode parent to previous board that affected this pattern
}
