├── 2048
    ├── src
    │   └── dk
    │   │   └── ahle
    │   │       └── thomas
    │   │           └── mcts2048
    │   │               ├── measure
    │   │                   ├── Measure.java
    │   │                   ├── ZeroMeasure.java
    │   │                   ├── FreesMeasure.java
    │   │                   ├── BestMeasure.java
    │   │                   ├── NegativeMeasure.java
    │   │                   ├── SumMeasure.java
    │   │                   ├── MonotonicityMeasure.java
    │   │                   ├── SmoothMeasure.java
    │   │                   └── EnsambleMeasure.java
    │   │               ├── strategy
    │   │                   ├── Strategy.java
    │   │                   ├── CyclicStrategy.java
    │   │                   ├── GreedyStrategy.java
    │   │                   ├── RandomStrategy.java
    │   │                   ├── SmoothStrategy.java
    │   │                   └── UCTStrategy.java
    │   │               ├── test
    │   │                   ├── TestUtils.java
    │   │                   ├── BoardTest.java
    │   │                   ├── MeasureTest.java
    │   │                   └── BitBoardTest.java
    │   │               ├── Main.java
    │   │               ├── Board.java
    │   │               └── BitBoards.java
    ├── .classpath
    └── .project
├── .gitignore
├── README.md
└── LICENSE


/2048/src/dk/ahle/thomas/mcts2048/measure/Measure.java:
--------------------------------------------------------------------------------
1 | package dk.ahle.thomas.mcts2048.measure;
2 | 
3 | import dk.ahle.thomas.mcts2048.Board;
4 | 
5 | public interface Measure {
6 | 	double score(Board board);
7 | }
8 | 


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/2048/src/dk/ahle/thomas/mcts2048/strategy/Strategy.java:
--------------------------------------------------------------------------------
1 | package dk.ahle.thomas.mcts2048.strategy;
2 | 
3 | import dk.ahle.thomas.mcts2048.Board;
4 | 
5 | public interface Strategy {
6 | 	public Board play(Board board);
7 | }
8 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/ZeroMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class ZeroMeasure implements Measure {
 6 | 	@Override
 7 | 	public double score(Board board) {
 8 | 		return 0;
 9 | 	}
10 | }
11 | 


--------------------------------------------------------------------------------
/2048/.classpath:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <classpath>
3 | 	<classpathentry kind="src" path="src"/>
4 | 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
5 | 	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/4"/>
6 | 	<classpathentry kind="output" path="bin"/>
7 | </classpath>
8 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/FreesMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class FreesMeasure implements Measure {
 6 | 	@Override
 7 | 	public double score(Board board) {
 8 | 		int frees = 0;
 9 | 		for (int p : Board.all) {
10 | 			if (board.grid()[p] == 0)
11 | 				frees++;
12 | 		}
13 | 		return frees;
14 | 	}
15 | }
16 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/BestMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class BestMeasure implements Measure {
 6 | 	@Override
 7 | 	public double score(Board board) {
 8 | 		int best = 0;
 9 | 		for (int p : Board.all) {
10 | 			best = Math.max(best, board.grid()[p]);
11 | 		}
12 | 		return best == 0 ? 0 : 1 << best;
13 | 	}
14 | }
15 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/NegativeMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class NegativeMeasure implements Measure {
 6 | 	Measure wrapped;
 7 | 
 8 | 	public NegativeMeasure(Measure wrapped) {
 9 | 		this.wrapped = wrapped;
10 | 	}
11 | 
12 | 	@Override
13 | 	public double score(Board board) {
14 | 		return -wrapped.score(board);
15 | 	}
16 | }
17 | 


--------------------------------------------------------------------------------
/2048/.project:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <projectDescription>
 3 | 	<name>2048</name>
 4 | 	<comment></comment>
 5 | 	<projects>
 6 | 	</projects>
 7 | 	<buildSpec>
 8 | 		<buildCommand>
 9 | 			<name>org.eclipse.jdt.core.javabuilder</name>
10 | 			<arguments>
11 | 			</arguments>
12 | 		</buildCommand>
13 | 	</buildSpec>
14 | 	<natures>
15 | 		<nature>org.eclipse.jdt.core.javanature</nature>
16 | 	</natures>
17 | </projectDescription>
18 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/SumMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class SumMeasure implements Measure {
 6 | 	/**
 7 | 	 * Returns the negative, exponential score. 
 8 | 	 */
 9 | 	@Override
10 | 	public double score(Board board) {
11 | 		int score = 0;
12 | 		for (int s : board.grid()) {
13 | 			if (s > 0)
14 | 				score += 1 << s;
15 | 		}
16 | 		return score;
17 | 	}
18 | }
19 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
 1 | *.class
 2 | 
 3 | # Mobile Tools for Java (J2ME)
 4 | .mtj.tmp/
 5 | 
 6 | # Package Files #
 7 | *.jar
 8 | *.war
 9 | *.ear
10 | 
11 | # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
12 | hs_err_pid*
13 | 
14 | # Eclipse
15 | .metadata
16 | .gradle
17 | bin/
18 | tmp/
19 | *.tmp
20 | *.bak
21 | *.swp
22 | *~.nib
23 | local.properties
24 | .settings/
25 | .loadpath
26 | .externalToolBuilders/
27 | *.launch
28 | .cproject
29 | .buildpath
30 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/MonotonicityMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class MonotonicityMeasure implements Measure {
 6 | 	@Override
 7 | 	public double score(Board board) {
 8 | 		int res = 0;
 9 | 		for (int m = 0; m <= 1; m++) {
10 | 			int dir = Board.dirs[m];
11 | 			for (int p : Board.orders[m]) {
12 | 				int a = (board.grid()[p] == 0 ? 0 : 1 << board.grid()[p]);
13 | 				int b = (board.grid()[p+dir] == 0 ? 0 : 1 << board.grid()[p+dir]);
14 | 				res += Math.abs(a-b);
15 | 			}
16 | 		}
17 | 		return res;
18 | 	}
19 | }
20 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/SmoothMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class SmoothMeasure implements Measure {
 6 | 	@Override
 7 | 	public double score(Board board) {
 8 | 		int res = 0;
 9 | 		for (int m = Board.UP; m <= Board.RIGHT; m++) {
10 | 			int dir = Board.dirs[m];
11 | 			for (int p : Board.orders[m]) {
12 | 				int a = (board.grid()[p] == 0 ? 0 : 1 << board.grid()[p]);
13 | 				int b = (board.grid()[p+dir] == 0 ? 0 : 1 << board.grid()[p+dir]);
14 | 				res += Math.abs(a-b);
15 | 			}
16 | 		}
17 | 		return res;
18 | 	}
19 | }
20 | 


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/2048/src/dk/ahle/thomas/mcts2048/strategy/CyclicStrategy.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.strategy;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class CyclicStrategy implements Strategy {
 6 | 	private int[] cycle;
 7 | 
 8 | 	public CyclicStrategy(int... moves) {
 9 | 		cycle = moves;
10 | 	}
11 | 
12 | 	@Override
13 | 	public Board play(Board board_) {
14 | 		Board board = board_.copy();
15 | 		int lst = 0;
16 | 		for (int pos = 0; pos - lst <= cycle.length + Board.moves.length; pos++) {
17 | 			board.unsafe_move(pos - lst <= cycle.length
18 | 					? cycle[pos % cycle.length]
19 | 					: Board.moves[pos % Board.moves.length]);
20 | 			if (board.changed) {
21 | 				board.unsafe_spawn();
22 | 				lst = pos;
23 | 			}
24 | 		}
25 | 		return board;
26 | 	}
27 | }
28 | 


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/2048/src/dk/ahle/thomas/mcts2048/measure/EnsambleMeasure.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.measure;
 2 | 
 3 | import java.util.ArrayList;
 4 | import java.util.List;
 5 | 
 6 | import dk.ahle.thomas.mcts2048.Board;
 7 | 
 8 | public class EnsambleMeasure implements Measure {
 9 | 	private List<Measure> measures = new ArrayList<>();
10 | 	private List<Double> weights = new ArrayList<>();
11 | 
12 | 	public EnsambleMeasure addMeasure(double weight, Measure measure) {
13 | 		weights.add(weight);
14 | 		measures.add(measure);
15 | 		return this;
16 | 	}
17 | 
18 | 	@Override
19 | 	public double score(Board board) {
20 | 		double score = 0;
21 | 		for (int i = 0; i < measures.size(); i++) {
22 | 			score += weights.get(i) * measures.get(i).score(board);
23 | 		}
24 | 		return score;
25 | 	}
26 | }
27 | 


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/2048/src/dk/ahle/thomas/mcts2048/test/TestUtils.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.test;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class TestUtils {
 6 | 
 7 | 	public static Board parse(String... ss) {
 8 | 		String r = "";
 9 | 		for (String s : ss)
10 | 			r += s;
11 | 		return parse(r);
12 | 	}
13 | 
14 | 	private static Board parse(String s) {
15 | 		Board board = new Board();
16 | 		for (int i = 0; i < 16; i++) {
17 | 			char c = s.charAt(i);
18 | 			if (c != '.')
19 | 				board.grid()[Board.all[i]] = c - '0';
20 | 		}
21 | 		return board;
22 | 	}
23 | 	
24 | 	public static long parseb(String... ss) {
25 | 		Board board = parse(ss);
26 | 		long res = 0;
27 | 		for (int i = 15; i >= 0; i--) {
28 | 			res <<= 4;
29 | 			res |= board.grid()[Board.all[i]];
30 | 		}
31 | 		return res;
32 | 	}
33 | }
34 | 


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/2048/src/dk/ahle/thomas/mcts2048/strategy/GreedyStrategy.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.strategy;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | import dk.ahle.thomas.mcts2048.measure.Measure;
 5 | 
 6 | /**
 7 |  * Strategy that tries to greedily maximise a given measure.
 8 |  */
 9 | public class GreedyStrategy implements Strategy {
10 | 
11 | 	private Measure measure;
12 | 	public GreedyStrategy(Measure measure) {
13 | 		this.measure = measure;
14 | 	}
15 | 	
16 | 	@Override
17 | 	public Board play(Board board) {
18 | 		while (true) {
19 | 			Board board1 = pickMove(board);
20 | 			if (board1 == null)
21 | 				break;
22 | 			board = board1;
23 | 			board.unsafe_spawn();
24 | 		}
25 | 		return board;
26 | 	}
27 | 	
28 | 	Board pickMove(Board board) {
29 | 		Board best = null;
30 | 		double bestS = -Double.MAX_VALUE;
31 | 		for (int move : Board.moves) {
32 | 			Board board1 = board.move(move);
33 | 			if (board1.changed) {
34 | 				double s = measure.score(board1);
35 | 				if (s >= bestS) {
36 | 					best = board1;
37 | 					bestS = s;
38 | 				}
39 | 			}
40 | 		}
41 | 		return best;
42 | 	}
43 | }
44 | 


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/2048/src/dk/ahle/thomas/mcts2048/strategy/RandomStrategy.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.strategy;
 2 | 
 3 | import java.security.InvalidParameterException;
 4 | import java.util.Random;
 5 | import java.util.concurrent.ThreadLocalRandom;
 6 | 
 7 | import dk.ahle.thomas.mcts2048.Board;
 8 | 
 9 | public class RandomStrategy implements Strategy {
10 | 	Random rand = ThreadLocalRandom.current();
11 | 	double[] chances;
12 | 	public RandomStrategy(double... chances) {
13 | 		if (chances.length != Board.moves.length)
14 | 			throw new InvalidParameterException();
15 | 		this.chances = chances;
16 | 	}
17 | 	public RandomStrategy() {
18 | 		this(.25, .25, .25, .25);
19 | 	}
20 | 	@Override
21 | 	public Board play(Board board) {
22 | 		while (!board.isStuck()) {
23 | 			board = board.move(pickMove());
24 | 			if (board.changed)
25 | 				board.unsafe_spawn();
26 | 		}
27 | 		return board;
28 | 	}
29 | 	private int pickMove() {
30 | 		double cul = 0;
31 | 		double r = rand.nextDouble();
32 | 		for (int i = 0; i < chances.length; i++) {
33 | 			cul += chances[i];
34 | 			if (r < cul)
35 | 				return i;
36 | 		}
37 | 		throw new InvalidParameterException("Check chances sum to 1");
38 | 	}
39 | }
40 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/test/BoardTest.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.test;
 2 | 
 3 | import static dk.ahle.thomas.mcts2048.test.TestUtils.parse;
 4 | import static org.junit.Assert.assertEquals;
 5 | 
 6 | import org.junit.Test;
 7 | 
 8 | import dk.ahle.thomas.mcts2048.Board;
 9 | 
10 | 
11 | public class BoardTest {
12 | 
13 | 	@Test
14 | 	public void testEquals() {
15 | 		assertEquals(
16 | 				parse("1...", "....", "....", "...."),
17 | 				parse("1...", "....", "....", "...."));
18 | 	}
19 | 	
20 | 	@Test
21 | 	public void testMoves() {
22 | 		assertEquals(
23 | 				parse("1111", "....", "....", "...."),
24 | 				parse("....", "....", "....", "1111").move(Board.UP));
25 | 		assertEquals(
26 | 				parse("....", "....", "....", "..22"),
27 | 				parse("....", "....", "....", "1111").move(Board.RIGHT));
28 | 		assertEquals(
29 | 			 	parse("....", "....", "....", "3..."),
30 | 			 	parse("....", "....", "....", "1111").move(Board.LEFT).move(Board.LEFT));
31 | 		assertEquals(
32 | 			 	parse("....", "....", "....", "2..."),
33 | 			 	parse("1...", "....", "1...", "....").move(Board.DOWN));
34 | 		assertEquals(
35 | 			 	parse("....", "....", "1...", "2..."),
36 | 			 	parse("1...", "....", "2...", "....").move(Board.DOWN));
37 | 	}
38 | }
39 | 


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/2048/src/dk/ahle/thomas/mcts2048/strategy/SmoothStrategy.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.strategy;
 2 | 
 3 | import dk.ahle.thomas.mcts2048.Board;
 4 | 
 5 | public class SmoothStrategy implements Strategy {
 6 | 
 7 | 	String kernel;
 8 | 	public SmoothStrategy(String kernel) {
 9 | 		this.kernel = kernel;
10 | 	}
11 | 	
12 | 	@Override
13 | 	public Board play(Board board) {
14 | 		while (true) {
15 | 			Board board1 = pickMove(board);
16 | 			if (board1 == null)
17 | 				break;
18 | 			board = board1;
19 | 			board.unsafe_spawn();
20 | //			board.print();
21 | 		}
22 | 		return board;
23 | 	}
24 | 	
25 | 	Board pickMove(Board board) {
26 | 		Board best = null;
27 | 		int bestS = Integer.MAX_VALUE;
28 | 		for (int move : Board.moves) {
29 | 			Board board1 = board.move(move);
30 | 			if (board1.changed) {
31 | 				int s = smoothness(board1);
32 | 				if (s <= bestS) {
33 | 					best = board1;
34 | 					bestS = s;
35 | 				}
36 | 			}
37 | 		}
38 | 		return best;
39 | 	}
40 | 	
41 | 	int smoothness(Board board) {
42 | 		int res = 0;
43 | 		for (int m = 0; m <= 1; m++) {
44 | 			int dir = Board.dirs[m];
45 | 			for (int p : Board.orders[m]) {
46 | 				res += kernel(p, p+dir);
47 | 			}
48 | 		}
49 | 		return res;
50 | 	}
51 | 	
52 | 	int kernel(int a, int b) {
53 | 		if (kernel.equals("id"))
54 | 			return Math.abs(a-b);
55 | 		if (kernel.equals("pow"))
56 | 			return Math.abs((1<<a)-(1<<b));
57 | 		throw new Error("Av");
58 | 	}
59 | }
60 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/test/MeasureTest.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.test;
 2 | 
 3 | import static dk.ahle.thomas.mcts2048.test.TestUtils.parse;
 4 | import static org.junit.Assert.assertEquals;
 5 | 
 6 | import org.junit.Test;
 7 | 
 8 | import dk.ahle.thomas.mcts2048.measure.FreesMeasure;
 9 | import dk.ahle.thomas.mcts2048.measure.Measure;
10 | import dk.ahle.thomas.mcts2048.measure.SmoothMeasure;
11 | import dk.ahle.thomas.mcts2048.measure.SumMeasure;
12 | 
13 | public class MeasureTest {
14 | 	@Test
15 | 	public void testSmoothPow() {
16 | 		Measure m = new SmoothMeasure();
17 | 		assertEquals(4, m.score(parse("1...", "....", "....", "....")), 1e-6);
18 | 		assertEquals(30+14, m.score(parse("1234", "....", "....", "....")), 1e-6);
19 | 		assertEquals(4*14, m.score(parse("1234", "1234", "1234", "1234")), 1e-6);
20 | 	}
21 | 	
22 | 	@Test
23 | 	public void testSum() {
24 | 		Measure m = new SumMeasure();
25 | 		assertEquals(2, m.score(parse("1...", "....", "....", "....")), 1e-6);
26 | 		assertEquals(30, m.score(parse("1234", "....", "....", "....")), 1e-6);
27 | 		assertEquals(4*30, m.score(parse("1234", "1234", "1234", "1234")), 1e-6);
28 | 	}
29 | 	
30 | 	@Test
31 | 	public void testFrees() {
32 | 		Measure m = new FreesMeasure();
33 | 		assertEquals(15, m.score(parse("1...", "....", "....", "....")), 1e-6);
34 | 		assertEquals(12, m.score(parse("1234", "....", "....", "....")), 1e-6);
35 | 		assertEquals(0, m.score(parse("1234", "1234", "1234", "1234")), 1e-6);
36 | 	}
37 | }
38 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/test/BitBoardTest.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048.test;
 2 | 
 3 | import static org.junit.Assert.assertEquals;
 4 | import static dk.ahle.thomas.mcts2048.test.TestUtils.*;
 5 | import static dk.ahle.thomas.mcts2048.BitBoards.*;
 6 | 
 7 | import org.junit.Test;
 8 | 
 9 | import dk.ahle.thomas.mcts2048.Board;
10 | 
11 | public class BitBoardTest {
12 | 
13 | 	@Test
14 | 	public void testReverse() {
15 | 		assertEquals(
16 | 						parseb("...1", "..3.", ".5..", "7..."),
17 | 				reverse(parseb("1...", ".3..", "..5.", "...7")));
18 | 	}
19 | 	
20 | 	@Test
21 | 	public void testFlip() {
22 | 		assertEquals(
23 | 					  parseb("1...", "2...", "3...", "4567"),
24 | 				trans(parseb("1234", "...5", "...6", "...7")));
25 | 	}
26 | 	
27 | 	@Test
28 | 	public void testMoves() {
29 | 		assertEquals(
30 | 				parseb("....", "....", "....", "..22"),
31 | 				move(parseb("....", "....", "....", "1111"),Board.RIGHT));
32 | 		assertEquals(
33 | 				parseb("1111", "....", "....", "...."),
34 | 				move(parseb("....", "....", "....", "1111"),Board.UP));
35 | 		assertEquals(
36 | 			 	parseb("....", "....", "....", "3..."),
37 | 			 	move(move(parseb("....", "....", "....", "1111"),Board.LEFT),Board.LEFT));
38 | 		assertEquals(
39 | 			 	parseb("....", "....", "....", "2..."),
40 | 			 	move(parseb("1...", "....", "1...", "...."),Board.DOWN));
41 | 		assertEquals(
42 | 			 	parseb("....", "....", "1...", "2..."),
43 | 			 	move(parseb("1...", "....", "2...", "...."),Board.DOWN));
44 | 		assertEquals(
45 | 				parseb("....", "51..", "242.", "4642"),
46 | 			 	move(move(move(move(parseb("2351", "4632", ".4..", ".11."),Board.UP),Board.RIGHT),Board.DOWN),Board.LEFT));
47 | 	}
48 | }
49 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | mcts-2048
 2 | =========
 3 | 
 4 | A Monte Carlo Tree Search AI for the game 2048.
 5 | Using bitboards and customizable strategies.
 6 | 
 7 | Compile:
 8 | 
 9 |     git clone git@github.com:thomasahle/mcts-2048.git
10 |     cd mcts-2048/2048
11 |     javac -cp src/ isrc/dk/ahle/thomas/mcts2048/Main.java
12 |     
13 | Run:
14 | 
15 |     java -cp src dk.ahle.thomas.mcts2048.Main
16 | 
17 |     ...
18 | 
19 |     7598.17444219067 / 493
20 |     7610.59842519685 / 508
21 |     9 11 12 9
22 |     5 6 8 5
23 |     1 3 4 3
24 |     2 1 2 1
25 |     
26 |     UCTStrategy Win%: 1.0, Avg: 7598.0, StdVar: 0.0, Min: 4096.0, Max: 4096.0, ms/m: 115.93982627007108
27 | 
28 | In this casse the maximum tile achieved was 4096.
29 | The sum of tiles on the board was 7598.
30 | Note the miniature board uses the log-2 base to display tiles, so 12 means 2^12 = 4048.
31 | 
32 | The default configuration above usually achives a max tile of 4,048 or 8,096, with 16,192 being a rare guest.
33 | 
34 | Options
35 | =======
36 | 
37 | The code supports multiple evaluation and rollout strategies.
38 | By default t uses the following:
39 | 
40 |     test(new UCTStrategy(1000, true,
41 |                     new SumMeasure(),
42 |                     new GreedyStrategy(new EnsambleMeasure()
43 |                             .addMeasure(-1, new SmoothMeasure())
44 |                             .addMeasure(1, new FreesMeasure()))), 1);
45 | 
46 | Which means it does 1000 roll-outs before each move to find the most promising.
47 | Each roll-out is done using a greedy strategy, which combines various herustics, by default optimsing for smoothness and free squares.
48 | The eventual node is evaluated using the `SumMeasure`, which means taking the sum of all tiles.
49 | Alternatively one could use the maximum tile or the score achived.
50 | 
51 | Another quite good strategy is the CyclicStrategy, which simply repeats a certain sequence of moves:
52 | 
53 |     test(new CyclicStrategy(Board.DOWN, Board.LEFT, Board.DOWN, Board.RIGHT), 1000);
54 |         
55 | It is also possible to use the CyclicStrategy for rollouts ini UCT:
56 | 
57 |     test(new UCTStrategy(1000, true,
58 |             new SumMeasure(),
59 |             new CyclicStrategy(Board.DOWN, Board.LEFT, Board.DOWN, Board.RIGHT), 1);
60 | 
61 | Inspiration
62 | ===========
63 | 
64 | The idea of using bitboards for faster move generation is inspired by https://github.com/nneonneo/2048-ai which uses min-max search.
65 | 
66 | For some state of the art papers, using n-tuple networks, see https://link.springer.com/chapter/10.1007/978-3-319-50935-8_8 and https://arxiv.org/pdf/1604.05085.pdf
67 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/Main.java:
--------------------------------------------------------------------------------
 1 | package dk.ahle.thomas.mcts2048;
 2 | 
 3 | import java.util.ArrayList;
 4 | import java.util.List;
 5 | 
 6 | import dk.ahle.thomas.mcts2048.measure.BestMeasure;
 7 | import dk.ahle.thomas.mcts2048.measure.EnsambleMeasure;
 8 | import dk.ahle.thomas.mcts2048.measure.FreesMeasure;
 9 | import dk.ahle.thomas.mcts2048.measure.NegativeMeasure;
10 | import dk.ahle.thomas.mcts2048.measure.SmoothMeasure;
11 | import dk.ahle.thomas.mcts2048.measure.SumMeasure;
12 | import dk.ahle.thomas.mcts2048.strategy.CyclicStrategy;
13 | import dk.ahle.thomas.mcts2048.strategy.GreedyStrategy;
14 | import dk.ahle.thomas.mcts2048.strategy.RandomStrategy;
15 | import dk.ahle.thomas.mcts2048.strategy.Strategy;
16 | import dk.ahle.thomas.mcts2048.strategy.UCTStrategy;
17 | 
18 | public class Main {
19 | 	public static void main(String[] args) {
20 | 		test(new UCTStrategy(1000, true,
21 | 				new SumMeasure(),
22 | 				new GreedyStrategy(new EnsambleMeasure()
23 | 					.addMeasure(-1, new SmoothMeasure())
24 | 					.addMeasure(1, new FreesMeasure()))), 1);
25 | 	}
26 | 	
27 | 	static void compareStrategies() {
28 | 		test(new CyclicStrategy(Board.DOWN, Board.LEFT, Board.DOWN, Board.RIGHT), 1000);
29 | 		test(new RandomStrategy(), 1000);
30 | 		test(new RandomStrategy(.01, .24, .5, .25), 1000);
31 | 		test(new GreedyStrategy(new FreesMeasure()), 1000);
32 | 		test(new GreedyStrategy(new NegativeMeasure(new SmoothMeasure())), 1000);
33 | 		test(new GreedyStrategy(new EnsambleMeasure()
34 | 				.addMeasure(-1, new SmoothMeasure())
35 | 				.addMeasure(1, new FreesMeasure())), 1000);
36 | 		test(new UCTStrategy(100, false,
37 | 				new SumMeasure(),
38 | 				new GreedyStrategy(new EnsambleMeasure()
39 | 					.addMeasure(-1, new SmoothMeasure())
40 | 					.addMeasure(1, new FreesMeasure()))), 10);
41 | 		test(new UCTStrategy(1000, false,
42 | 				new SumMeasure(),
43 | 				new GreedyStrategy(new EnsambleMeasure()
44 | 					.addMeasure(-1, new SmoothMeasure())
45 | 					.addMeasure(1, new FreesMeasure()))), 10);
46 | 	}
47 | 
48 | 	static void test(Strategy strat, int runs) {
49 | 		long time = System.currentTimeMillis();
50 | 		Board board = new Board();
51 | 		board.unsafe_spawn();
52 | 		board.unsafe_spawn();
53 | 		
54 | 		double loBest = Double.MAX_VALUE;
55 | 		double hiBest = -Double.MAX_VALUE;
56 | 		double wins = 0;
57 | 		List<Double> scores = new ArrayList<>();
58 | 		for (int i = 0; i < runs; i++) {
59 | 			Board result = strat.play(board);
60 | 			scores.add(new SumMeasure().score(result));
61 | 			double best = new BestMeasure().score(result);
62 | 			loBest = Math.min(loBest, best);
63 | 			hiBest = Math.max(hiBest, best);
64 | 			wins += best >= 2048 ? 1 : 0;
65 | 		}
66 | 		
67 | 		wins /= runs;
68 | 		
69 | 		double moves = 0;
70 | 		for (double score : scores) {
71 | 			moves += score / (2*.9 + 4*.1);
72 | 		}
73 | 		
74 | 		double avg = 0;
75 | 		for (double score : scores) {
76 | 			avg += score;
77 | 		}
78 | 		avg /= runs;
79 | 		double var = 0;
80 | 		for (double score : scores) {
81 | 			var += (score-avg)*(score-avg);
82 | 		}
83 | 		var = Math.sqrt(var/runs);
84 | 		
85 | 		double moveTime = (System.currentTimeMillis() - time)/moves;
86 | 		
87 | 		System.out.print(strat.getClass().getSimpleName() + " ");
88 | 		System.out.print("Win%: " + wins + ", ");
89 | 		System.out.print("Avg: " + avg + ", ");
90 | 		System.out.print("StdVar: " + var + ", ");
91 | 		System.out.print("Min: " + loBest + ", ");
92 | 		System.out.print("Max: " + hiBest + ", ");
93 | 		System.out.print("ms/m: " + moveTime);
94 | 		System.out.println();
95 | 	}
96 | }
97 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/Board.java:
--------------------------------------------------------------------------------
  1 | package dk.ahle.thomas.mcts2048;
  2 | 
  3 | import java.util.Arrays;
  4 | import java.util.Random;
  5 | import java.util.concurrent.ThreadLocalRandom;
  6 | 
  7 | 
  8 | public class Board {
  9 | 	public final static int orders[][] = {
 10 | 		{13, 14, 15, 16,  19, 20, 21, 22,  25, 26, 27, 28},
 11 | 		{9, 15, 21, 27,  8, 14, 20, 26,  7, 13, 19, 25},
 12 | 		{19, 20, 21, 22,  13, 14, 15, 16,  7, 8, 9, 10},
 13 | 		{8, 14, 20, 26,  9, 15, 21, 27,  10, 16, 22, 28},
 14 | 	};
 15 | 	public final static int all[] = {7, 8, 9, 10,  13, 14, 15, 16,  19, 20, 21, 22,  25, 26, 27, 28};
 16 | 	public final static int dirs[] = {-6, 1, 6, -1};
 17 | 	
 18 | 	public final static int UP = 0;
 19 | 	public final static int RIGHT = 1;
 20 | 	public final static int DOWN = 2;
 21 | 	public final static int LEFT = 3;
 22 | 	public final static int moves[] = {UP, RIGHT, DOWN, LEFT};
 23 | 	
 24 | 	private int[] grid = new int[] {
 25 | 		-1, -1, -1, -1, -1, -1,
 26 | 		-1,  0,  0,  0,  0, -1, 
 27 | 		-1,  0,  0,  0,  0, -1, 
 28 | 		-1,  0,  0,  0,  0, -1, 
 29 | 		-1,  0,  0,  0,  0, -1, 
 30 | 		-1, -1, -1, -1, -1, -1,
 31 | 	};
 32 | 	public boolean changed = false;
 33 | 
 34 | 	private Random rand = ThreadLocalRandom.current();
 35 | 	public void unsafe_spawn() {
 36 | 		while (true) {
 37 | 			int p = rand.nextInt(32);
 38 | 			if (grid()[p] == 0) {
 39 | 				grid()[p] = pickRandomly();
 40 | 				break;
 41 | 			}
 42 | 		}
 43 | 		// FIXME: Hangs if no spawn is available
 44 | 	}
 45 | 	
 46 | 	public int pickRandomly() {
 47 | 		return rand.nextInt(10) == 0 ? 2 : 1;
 48 | 	}
 49 | 	
 50 | 	public Board spawn() {
 51 | 		Board board1 = copy();
 52 | 		board1.unsafe_spawn();
 53 | 		return board1;
 54 | 	}
 55 | 	
 56 | 	boolean merged[] = new boolean[36];
 57 | 	public void unsafe_move(int move) {
 58 | 		Arrays.fill(merged, false);
 59 | 		changed = false;
 60 | 		int dir = dirs[move];
 61 | 		for (int src : orders[move]) {
 62 | 			if (grid[src] == 0)
 63 | 				continue;
 64 | 			int dst = src + dir;
 65 | 			// Move unto free squares
 66 | 			while (grid[dst] == 0) {
 67 | 				dst += dir;
 68 | 			}
 69 | 			// Merge
 70 | 			if (grid[dst] == grid[src] && !merged[dst]) {
 71 | 				grid[dst] += 1;
 72 | 				merged[dst] = true;
 73 | 				dst += dir;
 74 | 			}
 75 | 			// Normal termination
 76 | 			else {
 77 | 				grid[dst - dir] = grid[src];
 78 | 			}
 79 | 			// Move happened
 80 | 			if (dst != src + dir) {
 81 | 				grid[src] = 0;
 82 | 				changed = true;
 83 | 			}
 84 | 		}
 85 | 	}
 86 | 	
 87 | 	public Board move(int move) {
 88 | 		Board board = copy();
 89 | 		board.unsafe_move(move);
 90 | 		return board;
 91 | 	}
 92 | 	
 93 | 	public boolean isStuck() {
 94 | 		for (int p : all) {
 95 | 			if (grid()[p] == 0)
 96 | 				return false;
 97 | 			for (int dir : dirs) {
 98 | 				if (grid()[p+dir] == grid()[p])
 99 | 					return false;
100 | 			}
101 | 		}
102 | 		return true;
103 | 	}
104 | 	
105 | 	public boolean isFull() {
106 | 		for (int p : all) {
107 | 			if (grid()[p] == 0)
108 | 				return false;
109 | 		}
110 | 		return true;
111 | 	}
112 | 	
113 | 	public boolean canDirection(int move) {
114 | 		int dir = dirs[move];
115 | 		for (int p : orders[move]) {
116 | 			if (grid()[p+dir] == 0)
117 | 				return true;
118 | 			if (grid()[p+dir] == grid()[p])
119 | 				return true;
120 | 		}
121 | 		return false;
122 | 	}
123 | 
124 | 	public void print() {
125 | 		for (int i = 0; i < 36; i++) {
126 | 			if (grid()[i] == 0)
127 | 				System.out.print(" .");
128 | 			if (grid()[i] > 0)
129 | 				System.out.print(" " + grid()[i]);
130 | 			if (i % 6 == 0 && i != 0 && i != 6)
131 | 				System.out.println();
132 | 		}
133 | 		System.out.println();
134 | 	}
135 | 	
136 | 	public Board copy() {
137 | 		Board copy = new Board();
138 | 		System.arraycopy(grid(), 0, copy.grid(), 0, 36);
139 | 		return copy;
140 | 	}
141 | 
142 | 	@Override
143 | 	public int hashCode() {
144 | 		return Arrays.hashCode(grid());
145 | 	}
146 | 
147 | 	@Override
148 | 	public boolean equals(Object obj) {
149 | 		if (this == obj)
150 | 			return true;
151 | 		if (obj == null)
152 | 			return false;
153 | 		if (!(obj instanceof Board))
154 | 			return false;
155 | 		Board other = (Board) obj;
156 | 		if (!Arrays.equals(grid(), other.grid()))
157 | 			return false;
158 | 		return true;
159 | 	}
160 | 
161 | 	@Override
162 | 	public String toString() {
163 | 		String s = "";
164 | 		for (int p : all) {
165 | 			s += (char)(grid()[p]==0 ? '.' : grid()[p]+'0');
166 | 			if (p%6==4) s += " ";
167 | 		}
168 | 		return "Board [grid=" + s + "]";
169 | 	}
170 | 
171 | 	public int[] grid() {
172 | 		return grid;
173 | 	}
174 | }
175 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/BitBoards.java:
--------------------------------------------------------------------------------
  1 | package dk.ahle.thomas.mcts2048;
  2 | 
  3 | import java.util.Random;
  4 | 
  5 | /**
  6 |  * Format:
  7 |  * [63-60][59-56][55-52][51-48]
  8 |  * [47-44][43-40][39-36][35-32]
  9 |  * [31-28][27-24][23-20][19-16]
 10 |  * [15-12][11- 8][ 7- 4][ 3- 0]
 11 |  */
 12 | 
 13 | public class BitBoards {
 14 | 	private static Random rand = new Random();
 15 | 
 16 | 	public final static int UP = 0;
 17 | 	public final static int RIGHT = 1;
 18 | 	public final static int DOWN = 2;
 19 | 	public final static int LEFT = 3;
 20 | 	public final static int moves[] = { UP, RIGHT, DOWN, LEFT };
 21 | 
 22 | 	private final static short[] move_table = new short[0x10000];
 23 | 	
 24 | 	static {
 25 | 		Board board = new Board();
 26 | 		for (int row = 0; row <= 0xffff; row++) {
 27 | 			board.grid()[Board.all[0]] = row & 0xf;
 28 | 			board.grid()[Board.all[1]] = row >>> 4 & 0xf;
 29 | 			board.grid()[Board.all[2]] = row >>> 8 & 0xf;
 30 | 			board.grid()[Board.all[3]] = row >>> 12 & 0xf;
 31 | 			board = board.move(Board.RIGHT);
 32 | 			short out = (short)board.grid()[Board.all[0]];
 33 | 			out |= (short)board.grid()[Board.all[1]] << 4;
 34 | 			out |= (short)board.grid()[Board.all[2]] << 8;
 35 | 			out |= (short)board.grid()[Board.all[3]] << 12;
 36 | 			move_table[row] = out;
 37 | 		}
 38 | 	}
 39 | 	
 40 | 	/**
 41 | 	 * Transposes the board, one diagonal at the time.
 42 | 	 */
 43 | 	public static long trans(long board) {
 44 | 		long res = 0;
 45 | 		res |= board <<  4*9 & 0x000f000000000000L;
 46 | 		res |= board <<  4*6 & 0x00f0000f00000000L;
 47 | 		res |= board <<  4*3 & 0x0f0000f0000f0000L;
 48 | 		res |= board         & 0xf0000f0000f0000fL;
 49 | 		res |= board >>> 4*3 & 0x0000f0000f0000f0L;
 50 | 		res |= board >>> 4*6 & 0x00000000f0000f00L;
 51 | 		res |= board >>> 4*9 & 0x000000000000f000L;
 52 | 		return res;
 53 | 	}
 54 | 	
 55 | 	/**
 56 | 	 * Reverses the board along the row axis.
 57 | 	 */
 58 | 	public static long reverse(long board) {
 59 | 		board = (board << 8 & 0xff00ff00ff00ff00L)
 60 | 				| (board >>> 8 & 0x00ff00ff00ff00ffL);
 61 | 		board = (board << 4 & 0xf0f0f0f0f0f0f0f0L)
 62 | 				| (board >>> 4 & 0x0f0f0f0f0f0f0f0fL);
 63 | 		return board;
 64 | 	}
 65 | 	
 66 | 	/**
 67 | 	 * Isolates the row'th row, moves it with the move_table, and shifts it
 68 | 	 * back.
 69 | 	 */
 70 | 	private static long move_row_right(long board, int row) {
 71 | 		int b = (int)(board >>> 16*row) & 0xffff;
 72 | 		// move_table is a short[], so to avoid sign issues, we need to and with 0xffff
 73 | 		board = (long)move_table[b] & 0xffff;
 74 | 		return board << 16*row;
 75 | 	}
 76 | 	
 77 | 	private static long move_up(long board) {
 78 | 		return trans(move_left(trans(board)));
 79 | 	}
 80 | 	
 81 | 	private static long move_right(long board) {
 82 | 		return move_row_right(board, 0)
 83 | 				| move_row_right(board, 1)
 84 | 				| move_row_right(board, 2)
 85 | 				| move_row_right(board, 3);
 86 | 	}
 87 | 	
 88 | 	private static long move_down(long board) {
 89 | 		return trans(move_right(trans(board)));
 90 | 	}
 91 | 	
 92 | 	private static long move_left(long board) {
 93 | 		return reverse(move_right(reverse(board)));
 94 | 	}
 95 | 	
 96 | 	public static long move(long board, int move) {
 97 | 		switch (move) {
 98 | 		case UP:
 99 | 			return move_up(board);
100 | 		case RIGHT:
101 | 			return move_right(board);
102 | 		case DOWN:
103 | 			return move_down(board);
104 | 		case LEFT:
105 | 			return move_left(board);
106 | 		default:
107 | 			return 0;
108 | 		}
109 | 	}
110 | 
111 | 	public static int frees(long b) {
112 | 		int free = 0;
113 | 		while (b != 0) {
114 | 			free += ~(b | b>>>1 | b>>>2 | b>>>3) & 1;
115 | 			b >>>= 4;
116 | 		}
117 | 		return free;
118 | 	}
119 | 	
120 | 	public static long spawn(long board) {
121 | 		// asserts there is a free spot 
122 | 		int p = rand.nextInt(frees(board));
123 | 		int i = 0;
124 | 		while (p != -1) {
125 | 			if ((board >>> i*4 & 0xf) == 0)
126 | 				p--;
127 | 			i++;
128 | 		}
129 | 		return board | pickRandomly() << 4*(i-1);
130 | 	}
131 | 	
132 | 	public static long pickRandomly() {
133 | 		return rand.nextInt(10) == 0 ? 2 : 1;
134 | 	}
135 | 
136 | 	/**
137 | 	 * Not a very performant way of doing this.
138 | 	 */
139 | 	public static boolean isStuck(long board) {
140 | 		boolean res = false;
141 | 		for (int move = 0; move < 4; move++) {
142 | 			res |= canDirection(board, move);
143 | 		}
144 | 		return res;
145 | 	}
146 | 
147 | 	public static boolean canDirection(long board, int move) {
148 | 		return move(board, move) != board;
149 | 	}
150 | 
151 | 	public static void print(long board) {
152 | 		for (int i = 0; i < 16; i++) {
153 | 			long val = board >>> 4*i & 0xf;
154 | 			if (val == 0)
155 | 				System.out.print(" .");
156 | 			if (val > 0)
157 | 				System.out.print(" " + val);
158 | 			if ((i+1) % 4 == 0)
159 | 				System.out.println();
160 | 		}
161 | 		System.out.println();
162 | 	}
163 | }
164 | 


--------------------------------------------------------------------------------
/2048/src/dk/ahle/thomas/mcts2048/strategy/UCTStrategy.java:
--------------------------------------------------------------------------------
  1 | package dk.ahle.thomas.mcts2048.strategy;
  2 | 
  3 | import java.util.ArrayList;
  4 | import java.util.List;
  5 | import java.util.Random;
  6 | import java.util.concurrent.ThreadLocalRandom;
  7 | 
  8 | import dk.ahle.thomas.mcts2048.Board;
  9 | import dk.ahle.thomas.mcts2048.measure.Measure;
 10 | 
 11 | public class UCTStrategy implements Strategy {
 12 | 
 13 | 	static Measure rolloutMeasure;
 14 | 	static Strategy rolloutStrategy;
 15 | 	
 16 | 	private int expands;
 17 | 	private boolean verbose;
 18 | 
 19 | 	public UCTStrategy(int expands, boolean verbose, Measure rolloutMeasure, Strategy rolloutStrategy) {
 20 | 		this.expands = expands;
 21 | 		this.verbose = verbose;
 22 | 		UCTStrategy.rolloutMeasure = rolloutMeasure;
 23 | 		UCTStrategy.rolloutStrategy = rolloutStrategy;
 24 | 	}
 25 | 
 26 | 	@Override
 27 | 	public Board play(Board board) {
 28 | 		Node node = new ChoiceLeaf(board);
 29 | //		int k = 0;
 30 | 		while (!node.board().isStuck()) {
 31 | 			for (int i = 0; i < expands; i++) {
 32 | 				node = node.expand();
 33 | 			}
 34 | 			if (verbose) {
 35 | 				for (Node child : ((ChoiceNode)node).children) {
 36 | 					System.out.println((child.value()/child.visits())+" / "+child.visits());
 37 | 				}
 38 | 			}
 39 | 			
 40 | 			// Play the best move
 41 | 			node = node.select(false);
 42 | //			if (verbose) {
 43 | //				System.out.println(k++ +" "+node.value()/(node.visits()+1));
 44 | //			}
 45 | //			node.board().print();
 46 | 			// Play a random move
 47 | 			node = node.select(false);
 48 | 			
 49 | 			if (verbose) {
 50 | 				node.board().print();
 51 | 			}
 52 | 		}
 53 | 		return node.board();
 54 | 	}
 55 | }
 56 | 
 57 | abstract class Node {
 58 | 	/**
 59 | 	 * Expands some path.
 60 | 	 * 
 61 | 	 * @return The expanded node
 62 | 	 */
 63 | 	abstract Node expand();
 64 | 
 65 | 	/**
 66 | 	 * Select a child for expanding or moving.
 67 | 	 * 
 68 | 	 * @param explore Whether an exploration bonus should be included.
 69 | 	 * @return The most interesting child.
 70 | 	 */
 71 | 	abstract Node select(boolean explore);
 72 | 
 73 | 	int visits = 0;
 74 | 	double value = 0;
 75 | 	Board board;
 76 | 
 77 | 	Node(Board board) {
 78 | 		this.board = board;
 79 | 	}
 80 | 
 81 | 	/**
 82 | 	 * @return The number of calls to expand.
 83 | 	 */
 84 | 	int visits() {
 85 | 		return visits;
 86 | 	}
 87 | 
 88 | 	/**
 89 | 	 * @return The reward that has been generated yet by visiting this node.
 90 | 	 */
 91 | 	double value() {
 92 | 		return value;
 93 | 	}
 94 | 
 95 | 	/**
 96 | 	 * @return The current board wrapped by the node.
 97 | 	 */
 98 | 	Board board() {
 99 | 		return board;
100 | 	}
101 | }
102 | 
103 | class ChoiceNode extends Node {
104 | 	List<Node> children;
105 | 	private Random rand = ThreadLocalRandom.current();
106 | 	private final static double C = 1;
107 | 	private double leafValue;
108 | 
109 | 	public ChoiceNode(Board board, double leafValue, List<Node> children) {
110 | 		super(board);
111 | 		this.children = children;
112 | 		assert !children.isEmpty();
113 | 		
114 | 		value = leafValue;
115 | 		for (Node child : children) {
116 | 			value += child.value();
117 | 		}
118 | 		visits = 1 + children.size();
119 | 		
120 | 		this.leafValue = leafValue;
121 | 	}
122 | 
123 | 	@Override
124 | 	public Node expand() {
125 | 		Node node = select(true);
126 | 		double oldValue = node.value();
127 | 		
128 | 		Node node1 = node.expand();
129 | 		if (node != node1) {
130 | 			children.remove(node);
131 | 			children.add(node1);
132 | 		}
133 | 		
134 | 		visits += 1;
135 | 		value += node1.value() - oldValue;
136 | 
137 | 		return this;
138 | 	}
139 | 	
140 | 	@Override
141 | 	public Node select(boolean explore) {
142 | 		Node selected = null;
143 | 		double bestValue = -Double.MAX_VALUE;
144 | 		for (Node c : children) {
145 | 			double uctValue = c.value()/(c.visits()+1);
146 | 			if (explore) {
147 | 				
148 | 				uctValue += C * leafValue * Math.sqrt(Math.log(visits() + 1)/(c.visits() + 1));
149 | 				uctValue += rand.nextDouble()*1e-6;
150 | //				System.err.println(C * Math.sqrt(Math.log(visits() + 1)/(c.visits() + 1)));
151 | 			}
152 | 			if (uctValue >= bestValue) {
153 | 				selected = c;
154 | 				bestValue = uctValue;
155 | 			}
156 | 		}
157 | 		assert selected != null;
158 | 		return selected;
159 | 	}
160 | }
161 | 
162 | class ExitNode extends Node {
163 | 	private double leafValue;
164 | 	public ExitNode(Board board, double leafValue) {
165 | 		super(board);
166 | 		visits = 1;
167 | 		value = leafValue;
168 | 		this.leafValue = leafValue;
169 | 	}
170 | 
171 | 	@Override
172 | 	public Node expand() {
173 | 		visits += 1;
174 | 		value += leafValue;
175 | 		return this;
176 | 	}
177 | 
178 | 	@Override
179 | 	public Node select(boolean explore) {
180 | 		throw new UnsupportedOperationException();
181 | //		Alternatively, return null to signal no children
182 | 	}
183 | }
184 | 
185 | class ChoiceLeaf extends Node {
186 | 	public ChoiceLeaf(Board board) {
187 | 		super(board);
188 | 		visits = 1;
189 | 		value = UCTStrategy.rolloutMeasure.score(
190 | 				UCTStrategy.rolloutStrategy.play(board));
191 | 	}
192 | 
193 | 	@Override
194 | 	public Node expand() {
195 | 		List<Node> children = new ArrayList<>();
196 | 		for (int move : Board.moves) {
197 | 			Board board1 = board().move(move);
198 | 			if (board1.changed) {
199 | 				children.add(new SpawnNode(board1));
200 | 			}
201 | 		}
202 | 		if (children.isEmpty()) {
203 | 			return new ExitNode(board(), value());
204 | 		}
205 | 		return new ChoiceNode(board(), value(), children);
206 | 	}
207 | 
208 | 	@Override
209 | 	public Node select(boolean explore) {
210 | 		throw new UnsupportedOperationException();
211 | 		// Perhaps just return a random action?
212 | 	}
213 | }
214 | 
215 | class SpawnNode extends Node {
216 | 	private List<Node> children = new ArrayList<>();
217 | 
218 | 	/**
219 | 	 * True iff the last call to select spawned a new child
220 | 	 */
221 | 	private boolean wasNew;
222 | 
223 | 	public SpawnNode(Board board) {
224 | 		super(board);
225 | 		visits = 1;
226 | 		// We have to spawn before we play-out, as the Strategies expect to start with a choice
227 | 		value = UCTStrategy.rolloutMeasure.score(
228 | 				UCTStrategy.rolloutStrategy.play(board.spawn()));
229 | 	}
230 | 
231 | 	@Override
232 | 	public Node expand() {
233 | 		visits += 1;
234 | 		Node child = select(true);
235 | 		if (wasNew) {
236 | 			value += child.value();
237 | 		} else {
238 | 			double oldValue = child.value();
239 | 			Node child1 = child.expand();
240 | 			if (child != child1) {
241 | 				children.remove(child);
242 | 				children.add(child1);
243 | 			}
244 | 			value += child1.value() - oldValue;
245 | 		}
246 | 		return this;
247 | 	}
248 | 	
249 | 	@Override
250 | 	Node select(boolean explore) {
251 | 		// TODO: What if there are no possible spawns?
252 | 		Board board1 = board.spawn();
253 | 		for (Node child : children) {
254 | 			if (child.board().equals(board)) {
255 | 				wasNew = false;
256 | 				return child;
257 | 			}
258 | 		}
259 | 		// If we didn't already have a node representing the board, expand a bit
260 | 		Node child = new ChoiceLeaf(board1);
261 | 		children.add(child);
262 | 		wasNew = true;
263 | 		return child;
264 | 	}
265 | }
266 | 


--------------------------------------------------------------------------------
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467 | hereafter acquired, that would be infringed by some manner, permitted
468 | by this License, of making, using, or selling its contributor version,
469 | but do not include claims that would be infringed only as a
470 | consequence of further modification of the contributor version.  For
471 | purposes of this definition, "control" includes the right to grant
472 | patent sublicenses in a manner consistent with the requirements of
473 | this License.
474 | 
475 |   Each contributor grants you a non-exclusive, worldwide, royalty-free
476 | patent license under the contributor's essential patent claims, to
477 | make, use, sell, offer for sale, import and otherwise run, modify and
478 | propagate the contents of its contributor version.
479 | 
480 |   In the following three paragraphs, a "patent license" is any express
481 | agreement or commitment, however denominated, not to enforce a patent
482 | (such as an express permission to practice a patent or covenant not to
483 | sue for patent infringement).  To "grant" such a patent license to a
484 | party means to make such an agreement or commitment not to enforce a
485 | patent against the party.
486 | 
487 |   If you convey a covered work, knowingly relying on a patent license,
488 | and the Corresponding Source of the work is not available for anyone
489 | to copy, free of charge and under the terms of this License, through a
490 | publicly available network server or other readily accessible means,
491 | then you must either (1) cause the Corresponding Source to be so
492 | available, or (2) arrange to deprive yourself of the benefit of the
493 | patent license for this particular work, or (3) arrange, in a manner
494 | consistent with the requirements of this License, to extend the patent
495 | license to downstream recipients.  "Knowingly relying" means you have
496 | actual knowledge that, but for the patent license, your conveying the
497 | covered work in a country, or your recipient's use of the covered work
498 | in a country, would infringe one or more identifiable patents in that
499 | country that you have reason to believe are valid.
500 | 
501 |   If, pursuant to or in connection with a single transaction or
502 | arrangement, you convey, or propagate by procuring conveyance of, a
503 | covered work, and grant a patent license to some of the parties
504 | receiving the covered work authorizing them to use, propagate, modify
505 | or convey a specific copy of the covered work, then the patent license
506 | you grant is automatically extended to all recipients of the covered
507 | work and works based on it.
508 | 
509 |   A patent license is "discriminatory" if it does not include within
510 | the scope of its coverage, prohibits the exercise of, or is
511 | conditioned on the non-exercise of one or more of the rights that are
512 | specifically granted under this License.  You may not convey a covered
513 | work if you are a party to an arrangement with a third party that is
514 | in the business of distributing software, under which you make payment
515 | to the third party based on the extent of your activity of conveying
516 | the work, and under which the third party grants, to any of the
517 | parties who would receive the covered work from you, a discriminatory
518 | patent license (a) in connection with copies of the covered work
519 | conveyed by you (or copies made from those copies), or (b) primarily
520 | for and in connection with specific products or compilations that
521 | contain the covered work, unless you entered into that arrangement,
522 | or that patent license was granted, prior to 28 March 2007.
523 | 
524 |   Nothing in this License shall be construed as excluding or limiting
525 | any implied license or other defenses to infringement that may
526 | otherwise be available to you under applicable patent law.
527 | 
528 |   12. No Surrender of Others' Freedom.
529 | 
530 |   If conditions are imposed on you (whether by court order, agreement or
531 | otherwise) that contradict the conditions of this License, they do not
532 | excuse you from the conditions of this License.  If you cannot convey a
533 | covered work so as to satisfy simultaneously your obligations under this
534 | License and any other pertinent obligations, then as a consequence you may
535 | not convey it at all.  For example, if you agree to terms that obligate you
536 | to collect a royalty for further conveying from those to whom you convey
537 | the Program, the only way you could satisfy both those terms and this
538 | License would be to refrain entirely from conveying the Program.
539 | 
540 |   13. Remote Network Interaction; Use with the GNU General Public License.
541 | 
542 |   Notwithstanding any other provision of this License, if you modify the
543 | Program, your modified version must prominently offer all users
544 | interacting with it remotely through a computer network (if your version
545 | supports such interaction) an opportunity to receive the Corresponding
546 | Source of your version by providing access to the Corresponding Source
547 | from a network server at no charge, through some standard or customary
548 | means of facilitating copying of software.  This Corresponding Source
549 | shall include the Corresponding Source for any work covered by version 3
550 | of the GNU General Public License that is incorporated pursuant to the
551 | following paragraph.
552 | 
553 |   Notwithstanding any other provision of this License, you have
554 | permission to link or combine any covered work with a work licensed
555 | under version 3 of the GNU General Public License into a single
556 | combined work, and to convey the resulting work.  The terms of this
557 | License will continue to apply to the part which is the covered work,
558 | but the work with which it is combined will remain governed by version
559 | 3 of the GNU General Public License.
560 | 
561 |   14. Revised Versions of this License.
562 | 
563 |   The Free Software Foundation may publish revised and/or new versions of
564 | the GNU Affero General Public License from time to time.  Such new versions
565 | will be similar in spirit to the present version, but may differ in detail to
566 | address new problems or concerns.
567 | 
568 |   Each version is given a distinguishing version number.  If the
569 | Program specifies that a certain numbered version of the GNU Affero General
570 | Public License "or any later version" applies to it, you have the
571 | option of following the terms and conditions either of that numbered
572 | version or of any later version published by the Free Software
573 | Foundation.  If the Program does not specify a version number of the
574 | GNU Affero General Public License, you may choose any version ever published
575 | by the Free Software Foundation.
576 | 
577 |   If the Program specifies that a proxy can decide which future
578 | versions of the GNU Affero General Public License can be used, that proxy's
579 | public statement of acceptance of a version permanently authorizes you
580 | to choose that version for the Program.
581 | 
582 |   Later license versions may give you additional or different
583 | permissions.  However, no additional obligations are imposed on any
584 | author or copyright holder as a result of your choosing to follow a
585 | later version.
586 | 
587 |   15. Disclaimer of Warranty.
588 | 
589 |   THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
590 | APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
591 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
592 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
593 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
594 | PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
595 | IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
596 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
597 | 
598 |   16. Limitation of Liability.
599 | 
600 |   IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
601 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
602 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
603 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
604 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
605 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
606 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
607 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
608 | SUCH DAMAGES.
609 | 
610 |   17. Interpretation of Sections 15 and 16.
611 | 
612 |   If the disclaimer of warranty and limitation of liability provided
613 | above cannot be given local legal effect according to their terms,
614 | reviewing courts shall apply local law that most closely approximates
615 | an absolute waiver of all civil liability in connection with the
616 | Program, unless a warranty or assumption of liability accompanies a
617 | copy of the Program in return for a fee.
618 | 
619 |                      END OF TERMS AND CONDITIONS
620 | 
621 |             How to Apply These Terms to Your New Programs
622 | 
623 |   If you develop a new program, and you want it to be of the greatest
624 | possible use to the public, the best way to achieve this is to make it
625 | free software which everyone can redistribute and change under these terms.
626 | 
627 |   To do so, attach the following notices to the program.  It is safest
628 | to attach them to the start of each source file to most effectively
629 | state the exclusion of warranty; and each file should have at least
630 | the "copyright" line and a pointer to where the full notice is found.
631 | 
632 |     <one line to give the program's name and a brief idea of what it does.>
633 |     Copyright (C) <year>  <name of author>
634 | 
635 |     This program is free software: you can redistribute it and/or modify
636 |     it under the terms of the GNU Affero General Public License as published
637 |     by the Free Software Foundation, either version 3 of the License, or
638 |     (at your option) any later version.
639 | 
640 |     This program is distributed in the hope that it will be useful,
641 |     but WITHOUT ANY WARRANTY; without even the implied warranty of
642 |     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
643 |     GNU Affero General Public License for more details.
644 | 
645 |     You should have received a copy of the GNU Affero General Public License
646 |     along with this program.  If not, see <http://www.gnu.org/licenses/>.
647 | 
648 | Also add information on how to contact you by electronic and paper mail.
649 | 
650 |   If your software can interact with users remotely through a computer
651 | network, you should also make sure that it provides a way for users to
652 | get its source.  For example, if your program is a web application, its
653 | interface could display a "Source" link that leads users to an archive
654 | of the code.  There are many ways you could offer source, and different
655 | solutions will be better for different programs; see section 13 for the
656 | specific requirements.
657 | 
658 |   You should also get your employer (if you work as a programmer) or school,
659 | if any, to sign a "copyright disclaimer" for the program, if necessary.
660 | For more information on this, and how to apply and follow the GNU AGPL, see
661 | <http://www.gnu.org/licenses/>.


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