update mcts, incremental merge (#311)

* mcts v1, v2, v3, v4 done. v5 wip

* update mcts

* mcts v1, v2, v3, v4 done. v5 wip

* update mcts

* Merge changes on dev

* update mcts

---------

Co-authored-by: ramollia <>
This commit is contained in:
Bas Antonius de Jong
2026-01-17 04:05:11 +01:00
committed by GitHub
parent d078a70950
commit a6b2356a5e
15 changed files with 616 additions and 612 deletions

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@@ -1,193 +1,288 @@
package org.toop.game.players.ai;
import org.toop.framework.gameFramework.GameState;
import org.toop.framework.gameFramework.model.game.PlayResult;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.framework.gameFramework.model.player.AbstractAI;
import java.util.Random;
public class MCTSAI extends AbstractAI {
private static class Node {
public abstract class MCTSAI extends AbstractAI {
protected static class Node {
public TurnBasedGame state;
public long move;
public long unexpandedMoves;
public Node parent;
public int expanded;
public Node[] children;
public int visits;
public float value;
public int visits;
public float heuristic;
public float solved;
public Node(TurnBasedGame state, Node parent, long move) {
final long legalMoves = state.getLegalMoves();
public Node(TurnBasedGame state, long move, Node parent) {
this.state = state;
this.move = move;
this.unexpandedMoves = legalMoves;
this.parent = parent;
this.children = new Node[Long.bitCount(legalMoves)];
this.expanded = 0;
this.children = new Node[Long.bitCount(state.getLegalMoves())];
this.visits = 0;
this.value = 0.0f;
this.visits = 0;
this.heuristic = state.rateMove(move);
this.solved = Float.NaN;
}
public Node(TurnBasedGame state) {
this(state, 0L, null);
this(state, null, 0L);
}
public int getExpanded() {
return children.length - Long.bitCount(unexpandedMoves);
}
public boolean isFullyExpanded() {
return expanded >= children.length;
return unexpandedMoves == 0L;
}
float calculateUCT() {
float exploitation = visits <= 0? 0 : value / visits;
float exploration = 1.41f * (float)(Math.sqrt(Math.log(visits) / visits));
public float calculateUCT(int parentVisits) {
if (visits == 0) {
return Float.POSITIVE_INFINITY;
}
return exploitation + exploration;
final float exploitation = value / visits;
final float exploration = (float)(Math.sqrt(Math.log(parentVisits) / visits));
final float bias = heuristic * 10.0f / (visits + 1);
return exploitation + exploration + bias;
}
public Node bestUCTChild() {
int bestChildIndex = -1;
float bestScore = Float.NEGATIVE_INFINITY;
final int expanded = getExpanded();
Node highestUCTChild = null;
float highestUCT = Float.NEGATIVE_INFINITY;
for (int i = 0; i < expanded; i++) {
final float score = calculateUCT();
final float childUCT = children[i].calculateUCT(visits);
if (score > bestScore) {
bestChildIndex = i;
bestScore = score;
if (childUCT > highestUCT) {
highestUCTChild = children[i];
highestUCT = childUCT;
}
}
return bestChildIndex >= 0? children[bestChildIndex] : this;
return highestUCTChild;
}
}
private final int milliseconds;
protected static final ThreadLocal<Random> random = ThreadLocal.withInitial(Random::new);
protected final int milliseconds;
protected int lastIterations;
public MCTSAI(int milliseconds) {
this.milliseconds = milliseconds;
this.lastIterations = 0;
}
public MCTSAI(MCTSAI other) {
this.milliseconds = other.milliseconds;
this.lastIterations = other.lastIterations;
}
@Override
public MCTSAI deepCopy() {
return new MCTSAI(this);
public int getLastIterations() {
return lastIterations;
}
@Override
public long getMove(TurnBasedGame game) {
Node root = new Node(game.deepCopy());
long endTime = System.currentTimeMillis() + milliseconds;
while (System.currentTimeMillis() <= endTime) {
Node node = selection(root);
long legalMoves = node.state.getLegalMoves();
if (legalMoves != 0) {
node = expansion(node, legalMoves);
}
float result = 0.0f;
if (node.state.getLegalMoves() != 0) {
result = simulation(node.state, game.getCurrentTurn());
}
backPropagation(node, result);
protected Node selection(Node root) {
// while (Float.isNaN(root.solved) && root.isFullyExpanded() && !root.state.isTerminal()) {
while (root.isFullyExpanded() && !root.state.isTerminal()) {
root = root.bestUCTChild();
}
int mostVisitedIndex = -1;
int mostVisits = -1;
for (int i = 0; i < root.expanded; i++) {
if (root.children[i].visits > mostVisits) {
mostVisitedIndex = i;
mostVisits = root.children[i].visits;
}
}
return mostVisitedIndex != -1? root.children[mostVisitedIndex].move : randomSetBit(game.getLegalMoves());
return root;
}
private Node selection(Node node) {
while (node.state.getLegalMoves() != 0L && node.isFullyExpanded()) {
node = node.bestUCTChild();
protected Node expansion(Node leaf) {
if (leaf.unexpandedMoves == 0L) {
return leaf;
}
return node;
final long unexpandedMove = leaf.unexpandedMoves & -leaf.unexpandedMoves;
final TurnBasedGame copiedState = leaf.state.deepCopy();
copiedState.play(unexpandedMove);
final Node expandedChild = new Node(copiedState, leaf, unexpandedMove);
leaf.children[leaf.getExpanded()] = expandedChild;
leaf.unexpandedMoves &= ~unexpandedMove;
return expandedChild;
}
private Node expansion(Node node, long legalMoves) {
for (int i = 0; i < node.expanded; i++) {
legalMoves &= ~node.children[i].move;
protected float simulation(Node leaf) {
final TurnBasedGame copiedState = leaf.state.deepCopy();
final int playerIndex = 1 - copiedState.getCurrentTurn();
while (!copiedState.isTerminal()) {
final long legalMoves = copiedState.getLegalMoves();
final long randomMove = randomSetBit(legalMoves);
copiedState.play(randomMove);
}
if (legalMoves == 0L) {
return node;
if (copiedState.getWinner() == playerIndex) {
return 1.0f;
}
long move = randomSetBit(legalMoves);
TurnBasedGame copy = node.state.deepCopy();
copy.play(move);
Node newlyExpanded = new Node(copy, move, node);
node.children[node.expanded] = newlyExpanded;
node.expanded++;
return newlyExpanded;
}
private float simulation(TurnBasedGame state, int playerIndex) {
TurnBasedGame copy = state.deepCopy();
long legalMoves = copy.getLegalMoves();
PlayResult result = null;
while (legalMoves != 0) {
result = copy.play(randomSetBit(legalMoves));
legalMoves = copy.getLegalMoves();
}
if (result.state() == GameState.WIN) {
if (result.player() == playerIndex) {
return 1.0f;
}
if (copiedState.getWinner() >= 0) {
return -1.0f;
}
return -0.2f;
return 0.0f;
}
private void backPropagation(Node node, float value) {
while (node != null) {
node.visits++;
node.value += value;
node = node.parent;
protected void backPropagation(Node leaf, float value) {
while (leaf != null) {
leaf.value += value;
leaf.visits++;
if (Float.isNaN(leaf.solved)) {
updateSolvedStatus(leaf);
}
value = -value;
leaf = leaf.parent;
}
}
public static long randomSetBit(long value) {
Random random = new Random();
protected Node mostVisitedChild(Node root) {
final int expanded = root.getExpanded();
int count = Long.bitCount(value);
int target = random.nextInt(count);
Node mostVisitedChild = null;
int mostVisited = -1;
while (true) {
int bit = Long.numberOfTrailingZeros(value);
if (target == 0) {
return 1L << bit;
for (int i = 0; i < expanded; i++) {
if (root.children[i].visits > mostVisited) {
mostVisitedChild = root.children[i];
mostVisited = root.children[i].visits;
}
}
return mostVisitedChild;
}
protected Node findOrResetRoot(Node root, TurnBasedGame game) {
if (root == null) {
return new Node(game.deepCopy());
}
if (areStatesEqual(root.state.getBoard(), game.getBoard())) {
return root;
}
final int expanded = root.getExpanded();
for (int i = 0; i < expanded; i++) {
if (areStatesEqual(root.children[i].state.getBoard(), game.getBoard())) {
root.children[i].parent = null;
return root.children[i];
}
}
return new Node(game.deepCopy());
}
protected Node findChildByMove(Node root, long move) {
final int expanded = root.getExpanded();
for (int i = 0; i < expanded; i++) {
if (root.children[i].move == move) {
root.children[i].parent = null;
return root.children[i];
}
}
return null;
}
protected boolean areStatesEqual(long[] state1, long[] state2) {
if (state1.length != state2.length) {
return false;
}
for (int i = 0; i < state1.length; i++) {
if (state1[i] != state2[i]) {
return false;
}
}
return true;
}
protected long randomSetBit(long value) {
if (0L == value) {
return 0;
}
final int bitCount = Long.bitCount(value);
final int randomBitCount = random.get().nextInt(bitCount);
for (int i = 0; i < randomBitCount; i++) {
value &= value - 1;
target--;
}
return value & -value;
}
private void updateSolvedStatus(Node node) {
if (node.state.isTerminal()) {
final int winner = node.state.getWinner();
final int mover = 1 - node.state.getCurrentTurn();
node.solved = winner == mover? 1.0f : winner == -1? 0.0f : -1.0f;
return;
}
if (node.isFullyExpanded()) {
boolean allChildrenSolved = true;
boolean foundWinningMove = false;
boolean foundDrawMove = false;
for (final Node child : node.children) {
if (!Float.isNaN(child.solved)) {
if (child.solved == -1.0f) {
foundWinningMove = true;
break;
}
if (child.solved == 0.0f) {
foundDrawMove = true;
}
} else {
allChildrenSolved = false;
}
}
if (foundWinningMove) {
node.solved = 1.0f;
} else if (allChildrenSolved) {
node.solved = foundDrawMove? 0.0f : -1.0f;
}
}
}
}

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package org.toop.game.players.ai;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.framework.gameFramework.model.player.AbstractAI;
import java.util.Random;
public class MCTSAI2 extends AbstractAI {
private static class Node {
public TurnBasedGame state;
public long move;
public long unexpandedMoves;
public Node parent;
public Node[] children;
public int expanded;
public float value;
public int visits;
public Node(TurnBasedGame state, Node parent, long move) {
final long legalMoves = state.getLegalMoves();
this.state = state;
this.move = move;
this.unexpandedMoves = legalMoves;
this.parent = parent;
this.children = new Node[Long.bitCount(legalMoves)];
this.expanded = 0;
this.value = 0.0f;
this.visits = 0;
}
public Node(TurnBasedGame state) {
this(state, null, 0L);
}
public boolean isFullyExpanded() {
return expanded == children.length;
}
public float calculateUCT(int parentVisits) {
final float exploitation = value / visits;
final float exploration = 1.41f * (float)(Math.sqrt(Math.log(parentVisits) / visits));
return exploitation + exploration;
}
public Node bestUCTChild() {
Node highestUCTChild = null;
float highestUCT = Float.NEGATIVE_INFINITY;
for (int i = 0; i < expanded; i++) {
final float childUCT = children[i].calculateUCT(visits);
if (childUCT > highestUCT) {
highestUCTChild = children[i];
highestUCT = childUCT;
}
}
return highestUCTChild;
}
}
private final Random random;
private final int milliseconds;
public MCTSAI2(int milliseconds) {
this.random = new Random();
this.milliseconds = milliseconds;
}
public MCTSAI2(MCTSAI2 other) {
this.random = other.random;
this.milliseconds = other.milliseconds;
}
@Override
public MCTSAI2 deepCopy() {
return new MCTSAI2(this);
}
@Override
public long getMove(TurnBasedGame game) {
final Node root = new Node(game, null, 0L);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
while (System.nanoTime() < endTime) {
Node leaf = selection(root);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
final Node mostVisitedChild = mostVisitedChild(root);
return mostVisitedChild != null? mostVisitedChild.move : 0L;
}
private Node mostVisitedChild(Node root) {
Node mostVisitedChild = null;
int mostVisited = -1;
for (int i = 0; i < root.expanded; i++) {
if (root.children[i].visits > mostVisited) {
mostVisitedChild = root.children[i];
mostVisited = root.children[i].visits;
}
}
return mostVisitedChild;
}
private Node selection(Node root) {
while (root.isFullyExpanded() && !root.state.isTerminal()) {
root = root.bestUCTChild();
}
return root;
}
private Node expansion(Node leaf) {
if (leaf.unexpandedMoves == 0L) {
return leaf;
}
final long unexpandedMove = leaf.unexpandedMoves & -leaf.unexpandedMoves;
final TurnBasedGame copiedState = leaf.state.deepCopy();
copiedState.play(unexpandedMove);
final Node expandedChild = new Node(copiedState, leaf, unexpandedMove);
leaf.children[leaf.expanded] = expandedChild;
leaf.expanded++;
leaf.unexpandedMoves &= ~unexpandedMove;
return expandedChild;
}
private float simulation(Node leaf) {
final TurnBasedGame copiedState = leaf.state.deepCopy();
final int playerIndex = 1 - copiedState.getCurrentTurn();
while (!copiedState.isTerminal()) {
final long legalMoves = copiedState.getLegalMoves();
final long randomMove = randomSetBit(legalMoves);
copiedState.play(randomMove);
}
if (copiedState.getWinner() == playerIndex) {
return 1.0f;
} else if (copiedState.getWinner() >= 0) {
return -1.0f;
}
return 0.0f;
}
private void backPropagation(Node leaf, float value) {
while (leaf != null) {
leaf.value += value;
leaf.visits++;
value = -value;
leaf = leaf.parent;
}
}
private long randomSetBit(long value) {
if (0L == value) {
return 0;
}
final int bitCount = Long.bitCount(value);
final int randomBitCount = random.nextInt(bitCount);
for (int i = 0; i < randomBitCount; i++) {
value &= value - 1;
}
return value & -value;
}
}

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package org.toop.game.players.ai;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.framework.gameFramework.model.player.AbstractAI;
import java.util.Random;
public class MCTSAI3 extends AbstractAI {
private static class Node {
public TurnBasedGame state;
public long move;
public long unexpandedMoves;
public Node parent;
public Node[] children;
public int expanded;
public float value;
public int visits;
public Node(TurnBasedGame state, Node parent, long move) {
final long legalMoves = state.getLegalMoves();
this.state = state;
this.move = move;
this.unexpandedMoves = legalMoves;
this.parent = parent;
this.children = new Node[Long.bitCount(legalMoves)];
this.expanded = 0;
this.value = 0.0f;
this.visits = 0;
}
public Node(TurnBasedGame state) {
this(state, null, 0L);
}
public boolean isFullyExpanded() {
return expanded == children.length;
}
public float calculateUCT(int parentVisits) {
final float exploitation = value / visits;
final float exploration = 1.41f * (float)(Math.sqrt(Math.log(parentVisits) / visits));
return exploitation + exploration;
}
public Node bestUCTChild() {
Node highestUCTChild = null;
float highestUCT = Float.NEGATIVE_INFINITY;
for (int i = 0; i < expanded; i++) {
final float childUCT = children[i].calculateUCT(visits);
if (childUCT > highestUCT) {
highestUCTChild = children[i];
highestUCT = childUCT;
}
}
return highestUCTChild;
}
}
private final Random random;
private Node root;
private final int milliseconds;
public MCTSAI3(int milliseconds) {
this.random = new Random();
this.root = null;
this.milliseconds = milliseconds;
}
public MCTSAI3(MCTSAI3 other) {
this.random = other.random;
this.root = other.root;
this.milliseconds = other.milliseconds;
}
@Override
public MCTSAI3 deepCopy() {
return new MCTSAI3(this);
}
@Override
public long getMove(TurnBasedGame game) {
detectRoot(game);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
while (System.nanoTime() < endTime) {
Node leaf = selection(root);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
final Node mostVisitedChild = mostVisitedChild(root);
final long move = mostVisitedChild != null? mostVisitedChild.move : 0L;
newRoot(move);
return move;
}
private Node mostVisitedChild(Node root) {
Node mostVisitedChild = null;
int mostVisited = -1;
for (int i = 0; i < root.expanded; i++) {
if (root.children[i].visits > mostVisited) {
mostVisitedChild = root.children[i];
mostVisited = root.children[i].visits;
}
}
return mostVisitedChild;
}
private void detectRoot(TurnBasedGame game) {
if (root == null) {
root = new Node(game.deepCopy());
return;
}
final long[] currentBoards = game.getBoard();
final long[] rootBoards = root.state.getBoard();
boolean detected = true;
for (int i = 0; i < rootBoards.length; i++) {
if (rootBoards[i] != currentBoards[i]) {
detected = false;
break;
}
}
if (detected) {
return;
}
for (int i = 0; i < root.expanded; i++) {
final Node child = root.children[i];
final long[] childBoards = child.state.getBoard();
detected = true;
for (int j = 0; j < childBoards.length; j++) {
if (childBoards[j] != currentBoards[j]) {
detected = false;
break;
}
}
if (detected) {
root = child;
return;
}
}
root = new Node(game.deepCopy());
}
private void newRoot(long move) {
for (final Node child : root.children) {
if (child.move == move) {
root = child;
break;
}
}
}
private Node selection(Node root) {
while (root.isFullyExpanded() && !root.state.isTerminal()) {
root = root.bestUCTChild();
}
return root;
}
private Node expansion(Node leaf) {
if (leaf.unexpandedMoves == 0L) {
return leaf;
}
final long unexpandedMove = leaf.unexpandedMoves & -leaf.unexpandedMoves;
final TurnBasedGame copiedState = leaf.state.deepCopy();
copiedState.play(unexpandedMove);
final Node expandedChild = new Node(copiedState, leaf, unexpandedMove);
leaf.children[leaf.expanded] = expandedChild;
leaf.expanded++;
leaf.unexpandedMoves &= ~unexpandedMove;
return expandedChild;
}
private float simulation(Node leaf) {
final TurnBasedGame copiedState = leaf.state.deepCopy();
final int playerIndex = 1 - copiedState.getCurrentTurn();
while (!copiedState.isTerminal()) {
final long legalMoves = copiedState.getLegalMoves();
final long randomMove = randomSetBit(legalMoves);
copiedState.play(randomMove);
}
if (copiedState.getWinner() == playerIndex) {
return 1.0f;
} else if (copiedState.getWinner() >= 0) {
return -1.0f;
}
return 0.0f;
}
private void backPropagation(Node leaf, float value) {
while (leaf != null) {
leaf.value += value;
leaf.visits++;
value = -value;
leaf = leaf.parent;
}
}
private long randomSetBit(long value) {
if (0L == value) {
return 0;
}
final int bitCount = Long.bitCount(value);
final int randomBitCount = random.nextInt(bitCount);
for (int i = 0; i < randomBitCount; i++) {
value &= value - 1;
}
return value & -value;
}
}

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package org.toop.game.players.ai.mcts;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.game.players.ai.MCTSAI;
public class MCTSAI1 extends MCTSAI {
public MCTSAI1(int milliseconds) {
super(milliseconds);
}
public MCTSAI1(MCTSAI1 other) {
super(other);
}
@Override
public MCTSAI1 deepCopy() {
return new MCTSAI1(this);
}
@Override
public long getMove(TurnBasedGame game) {
final Node root = new Node(game, null, 0L);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
// while (Float.isNaN(root.solved) && System.nanoTime() < endTime) {
while (System.nanoTime() < endTime) {
Node leaf = selection(root);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
lastIterations = root.visits;
final Node mostVisitedChild = mostVisitedChild(root);
return mostVisitedChild.move;
}
}

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package org.toop.game.players.ai.mcts;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.game.players.ai.MCTSAI;
public class MCTSAI2 extends MCTSAI {
private Node root;
public MCTSAI2(int milliseconds) {
super(milliseconds);
this.root = null;
}
public MCTSAI2(MCTSAI2 other) {
super(other);
this.root = other.root;
}
@Override
public MCTSAI2 deepCopy() {
return new MCTSAI2(this);
}
@Override
public long getMove(TurnBasedGame game) {
root = findOrResetRoot(root, game);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
// while (Float.isNaN(root.solved) && System.nanoTime() < endTime) {
while (System.nanoTime() < endTime) {
Node leaf = selection(root);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
lastIterations = root.visits;
final Node mostVisitedChild = mostVisitedChild(root);
final long move = mostVisitedChild.move;
root = findChildByMove(root, move);
return move;
}
}

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package org.toop.game.players.ai.mcts;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.game.players.ai.MCTSAI;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class MCTSAI3 extends MCTSAI {
private final int threads;
public MCTSAI3(int milliseconds, int threads) {
super(milliseconds);
this.threads = threads;
}
public MCTSAI3(MCTSAI3 other) {
super(other);
this.threads = other.threads;
}
@Override
public MCTSAI3 deepCopy() {
return new MCTSAI3(this);
}
@Override
public long getMove(TurnBasedGame game) {
final ExecutorService pool = Executors.newFixedThreadPool(threads);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
final List<Callable<Node>> tasks = new ArrayList<>();
for (int i = 0; i < threads; i++) {
tasks.add(() -> {
final Node localRoot = new Node(game.deepCopy());
// while (Float.isNaN(localRoot.solved) && System.nanoTime() < endTime) {
while (System.nanoTime() < endTime) {
Node leaf = selection(localRoot);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
return localRoot;
});
}
try {
final List<Future<Node>> results = pool.invokeAll(tasks);
pool.shutdown();
final Node root = new Node(game.deepCopy());
for (int i = 0; i < root.children.length; i++) {
expansion(root);
}
for (final Future<Node> result : results) {
final Node localRoot = result.get();
for (final Node localChild : localRoot.children) {
for (int i = 0; i < root.children.length; i++) {
if (localChild.move == root.children[i].move) {
root.children[i].visits += localChild.visits;
root.visits += localChild.visits;
break;
}
}
}
}
lastIterations = root.visits;
final Node mostVisitedChild = mostVisitedChild(root);
return mostVisitedChild.move;
} catch (Exception _) {
lastIterations = 0;
final long legalMoves = game.getLegalMoves();
return randomSetBit(legalMoves);
}
}
}

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package org.toop.game.players.ai.mcts;
import org.toop.framework.gameFramework.model.game.TurnBasedGame;
import org.toop.game.players.ai.MCTSAI;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class MCTSAI4 extends MCTSAI {
private final int threads;
private final Node[] threadRoots;
public MCTSAI4(int milliseconds, int threads) {
super(milliseconds);
this.threads = threads;
this.threadRoots = new Node[threads];
}
public MCTSAI4(MCTSAI4 other) {
super(other);
this.threads = other.threads;
this.threadRoots = other.threadRoots;
}
@Override
public MCTSAI4 deepCopy() {
return new MCTSAI4(this);
}
@Override
public long getMove(TurnBasedGame game) {
for (int i = 0; i < threads; i++) {
threadRoots[i] = findOrResetRoot(threadRoots[i], game);
}
final ExecutorService pool = Executors.newFixedThreadPool(threads);
final long endTime = System.nanoTime() + milliseconds * 1_000_000L;
final List<Callable<Node>> tasks = new ArrayList<>();
for (int i = 0; i < threads; i++) {
final int threadIndex = i;
tasks.add(() -> {
final Node localRoot = threadRoots[threadIndex];
// while (Float.isNaN(localRoot.solved) && System.nanoTime() < endTime) {
while (System.nanoTime() < endTime) {
Node leaf = selection(localRoot);
leaf = expansion(leaf);
final float value = simulation(leaf);
backPropagation(leaf, value);
}
return localRoot;
});
}
try {
final List<Future<Node>> results = pool.invokeAll(tasks);
pool.shutdown();
final Node root = new Node(game.deepCopy());
for (int i = 0; i < root.children.length; i++) {
expansion(root);
}
for (final Future<Node> result : results) {
final Node localRoot = result.get();
for (final Node localChild : localRoot.children) {
for (int i = 0; i < root.children.length; i++) {
if (localChild.move == root.children[i].move) {
root.children[i].visits += localChild.visits;
root.visits += localChild.visits;
break;
}
}
}
}
lastIterations = root.visits;
final Node mostVisitedChild = mostVisitedChild(root);
final long move = mostVisitedChild.move;
for (int i = 0; i < threads; i++) {
threadRoots[i] = findChildByMove(threadRoots[i], move);
}
return move;
} catch (Exception _) {
lastIterations = 0;
final long legalMoves = game.getLegalMoves();
return randomSetBit(legalMoves);
}
}
}