/**
* Method for figureing out if a node is fully expanded yet or terminal
*
* @param n
* @return
*/
public Node treePolicy(Node n) {
// Node current = n;
while (!n.isTerminal()) { // Non terminal
if (!n.getExpanded()) { // Not fully expanded
return n.expand();
} else {
n = bestChild(n);
}
}
return n;
}
public static void main(String[] args) {
Node root = new Node(1);
root.left = new Node(2);
root.right = new Node(3);
root.left.left = new Node(4);
root.left.right = new Node(5);
root.left.right.left = new Node(7);
root.left.left.left = new Node(6);
root.right.right = new Node(8);
root.right.right.left = new Node(9);
print(root);
}
/**
* Method which simulates the game from a given node/state
*
* @param n
* @return
*/
private int defaultPolicy(Node n) {
Game currentState = n.getState().copy();
int d = 0;
while (!isStateTerminal(currentState) && d != depth) {
MOVE localCurrentDirection = null;
if (d == 0
|| currentState.isJunction(
currentState.getPacmanCurrentNodeIndex())) { // is in a junction
MOVE[] moves = currentState.getPossibleMoves(currentState.getPacmanCurrentNodeIndex());
int i = rng.nextInt(moves.length);
localCurrentDirection = moves[i];
while (moves[i] == localCurrentDirection.opposite()) {
i = rng.nextInt(moves.length);
}
localCurrentDirection = moves[i];
}
currentState.advanceGame(
localCurrentDirection,
controller.Controller.getGhostController().getMove(currentState, 0));
d++;
}
if (isStateTerminal(currentState)) {
return -1;
}
return currentState.getScore();
}
/**
* Method for finding the best child to explore
*
* @param n
* @return
*/
private Node bestChild(Node n) {
Node best = null;
double bestValue = Double.NEGATIVE_INFINITY;
for (Node c : n.getChildren().values()) {
double uctValue =
(c.getTotalValue() / c.getVisits())
+ COEFFICIENT * Math.sqrt((2 * Math.log(n.getVisits())) / (c.getVisits()));
uctValue +=
rng.nextDouble()
* 1e-6; // In case of same uctValue, this random will remove bias towards first
// checked child
if (bestValue < uctValue) {
bestValue = uctValue;
best = c;
}
}
// TESTING
if (best == null) {
System.out.println("BUGS");
}
//
return best;
}
/**
* Backup method
*
* @param next
* @param score
*/
private void backup(Node next, int score) {
Node current = next;
while (current != null) {
current = current.visit(score);
}
}