// returns the single move to make given a board, depth, piecelist, heuristic
// whill choose the best terminal board at the max depth,
// or if none exists, the best board with no children (inevitable death)
public Board.Direction nextMove(Board start, List<Integer> nextPiece) {
int maxDepth = Math.min(exploreDepth, nextPiece.size());
double bestLiveScore = -1;
Board.Direction bestLiveDirection = null; // cus why not?
// add the first round seperately so we know which move to return
for (Board.Direction d : Board.Direction.values()) {
Board next = start.move(d, nextPiece.get(0));
if (next != null) {
PriorityQueue<Double> pq = new PriorityQueue<Double>();
Deque<StackItem> stack = new ArrayDeque<StackItem>();
stack.push(new StackItem(next, 1, d));
// DFS
while (!stack.isEmpty()) {
StackItem cur = stack.pop();
// add more moves if not beyond max depth
if (cur.d < maxDepth) {
for (Board.Direction d2 : Board.Direction.values()) {
Board next2 = cur.b.move(d2, nextPiece.get(cur.d));
if (next2 != null) {
stack.push(new StackItem(next2, cur.d + 1, cur.move));
}
}
}
// update live only at the bottom of the tree
if (cur.d == maxDepth) {
pq.add(heuristic.useHeuristic(cur.b));
if (pq.size() > 10) pq.poll();
}
}
double sum = 0;
int count = 0;
count = pq.size();
while (!pq.isEmpty()) sum += pq.poll();
if (count > 0 && sum / count > bestLiveScore) {
bestLiveScore = sum / count;
bestLiveDirection = d;
}
}
}
return bestLiveDirection;
}
public int astar(Vertex start, Vertex goal, Heuristic h) {
int count;
Collection<Vertex> vertices_;
Comparator<Vertex> comp;
PriorityQueue<Vertex> fringe;
count = 0;
vertices_ = vertices.values();
comp =
new Comparator<Vertex>() {
public int compare(Vertex i, Vertex j) {
return (i.cost + i.estimate - j.cost - j.estimate);
}
}; // use estimates
fringe = new PriorityQueue<Vertex>(20, comp);
for (Vertex v : vertices_) {
v.visited = false;
v.cost = 999999;
}
start.cost = 0;
start.parent = null;
fringe.add(start);
while (!fringe.isEmpty()) {
Vertex v = fringe.remove(); // lowest-cost
count++; // count nodes
if (v.equals(goal)) { // if the goal is found, quit
break;
}
if (!v.visited) {
v.visited = true;
for (Edge e : v.edges) {
int newcost = v.cost + e.cost;
if (newcost < e.target.cost) {
e.target.cost = newcost;
e.target.parent = v;
e.target.estimate = h.fn(e.target, goal); // use heuristic
fringe.add(e.target);
}
}
}
}
return count;
}
