/// <summary>
/// Recursively search for the best move for the given board
/// </summary>
/// <param name="depth">How many recursive iterations you want to take(each iteration is 1 turn of 1 of the players, so steps ahead is depth/2</param>
/// <param name="tiles">The Tile to iterate over</param>
/// <param name="initialSequence">Initial sequence of moves, which is used as state to know what sequence </param>
/// <param name="priority"></param>
/// <param name="max"></param>
/// <param name="currentPlayer"></param>
/// <param name="enemyPlayer"></param>
/// <returns></returns>
public MinimaxResult GetBestTurn(BoardTileCollection tiles, IPlayer currentPlayer)
{
#if DEBUG
this._amountOfCheckups = 0;
#endif
IPlayer enemyPlayer = this.Game.GetEnemyPlayer(currentPlayer);
var results = new List <MinimaxResult>();
//get all possible initial moves for the player
var checkerMovePairs = currentPlayer.GetAllPossibleMoves(Game, enemyPlayer, tiles);
Parallel.ForEach(checkerMovePairs, (pair, loopState) => {
List <MoveSequence> possibleSequences = null;
Turn turn = pair.Value;
foreach (var move in turn.Moves) //for each initial move of the checker
{
if (move is AttackMove attMove)
{
//all possible followup move sequences
possibleSequences = GetPossibleMoveSequences(turn, attMove);
}
else if (move is WalkMove)
{
possibleSequences = new List <MoveSequence> {
new MoveSequence(turn, new List <Move> {
move
})
};
}
//in case theres only 1 possible move, we dont need to calculate anything, so cut of.
if (checkerMovePairs.Count == 1 && possibleSequences.Count == 1)
{
var seq = possibleSequences.First();
results.Add(new MinimaxResult(seq.Moves, seq.Turn, 0));
loopState.Break();
}
foreach (var sequence in possibleSequences)
{
BoardTileCollection clonedTiles = (BoardTileCollection)tiles.Clone();
float prio = sequence.Moves[0].Priority;
foreach (var mov in sequence.Moves)
{
Board.TakeMove(clonedTiles, mov);
}
//now we need to call search the move tree for the value of the sequence.
var sequenceValue = GetValueOfMoveSequence(this.MaxDepth - 1, clonedTiles, prio, enemyPlayer, currentPlayer, false);
var result = new MinimaxResult(sequence.Moves, sequence.Turn, sequenceValue);
lock (_resultAddLock)
results.Add(result);
}
}
});
#if DEBUG
Console.WriteLine($"amount of checkups: {this._amountOfCheckups}");
#endif
return(ChooseBestResult(results));
}
public void WinEndsTheSearchForPlayerY()
{
HexBoard board = new HexBoard(5);
PlayToWinInOneMove(board, false);
Minimax minimax = MakeMinimaxForBoard(board);
const int SearchDepth = 4;
MinimaxResult bestMove = minimax.DoMinimax(SearchDepth, false);
Location win = new Location(0, 3);
Assert.AreEqual(win, bestMove.Move, "wrong win location");
// do: test that locations after 0, 4 aren't even looked at. A win ends the search
IList <Location> locationsExamined = minimax.DebugDataItems
.Where(d => d.Lookahead == SearchDepth)
.Select(d => d.Location).ToList();
Assert.IsTrue(locationsExamined.Count > 0, "No locations examined");
Assert.IsTrue(locationsExamined.Contains(win), "Locations examined does not contain win");
Location unexpected = new Location(4, 4);
Assert.IsFalse(locationsExamined.Contains(unexpected), "Should not have examined location " + unexpected + " after win");
}
private void checkMoves(MouseState mouseState)
{
MouseState currentMouseState = mouseState;
Point mousePosition = new Point(currentMouseState.X, currentMouseState.Y);
if (board.CurrentPlayer() == human)
{
if (lastMouseState.LeftButton == ButtonState.Pressed && currentMouseState.LeftButton == ButtonState.Released)
{
foreach (KeyValuePair <Point, Rectangle> boundingBox in boundingBoxes)
{
if (boundingBox.Value.Contains(mousePosition))
{
board.MakeMove(new Move(boundingBox.Key), human);
}
}
}
}
else
{
MinimaxResult result = Minimax.Do(board, cpu, GameSettings.Difficulty, 0);
Move move = result.GetMove();
board.MakeMove(move, cpu);
}
currentTurn = board.CurrentPlayer();
}
/// <summary>
/// public wrapper for recursion
/// try each possible move, find the one with the best score
/// </summary>
/// <param name="lookahead">how far to look ahead</param>
/// <param name="playerX">is this for player x</param>
/// <returns>The data on the best move location and score</returns>
public MinimaxResult DoMinimax(int lookahead, bool playerX)
{
// set up inital state
DateTime startTime = DateTime.Now;
if (lookahead < 1)
{
throw new Exception("Invalid lookahead of " + lookahead);
}
this.debugDataItems.Clear();
Occupied player = playerX.ToPlayer();
int alpha = MoveScoreConverter.ConvertWin(player.Opponent(), 0);
int beta = MoveScoreConverter.ConvertWin(player, 0);
MinimaxResult bestMove = this.ScoreBoard(lookahead, this.ActualBoard, playerX, alpha, beta);
if (bestMove.Move != Location.Null)
{
GoodMoves.AddGoodMove(0, bestMove.Move);
}
DateTime endTime = DateTime.Now;
this.MoveTime = endTime - startTime;
return(bestMove);
}
private void DoMove()
{
Minimax hexPlayer = new Minimax(this.hexGame.Board, this.hexGame.GoodMoves, this.MakeCandiateMovesFinder());
MinimaxResult minimaxResult = hexPlayer.DoMinimax(4, this.MoveIsPlayerX());
this.PlayLocation = this.GetBestMove(minimaxResult);
this.MoveTime = hexPlayer.MoveTime;
this.CallCompletedAction();
}
private static void DoTestTestNoLingering2Win(Minimax minimax, int depth)
{
MinimaxResult bestMove = minimax.DoMinimax(depth, true);
// play here to win
Location expectedMove = new Location(2, 2);
Assert.AreEqual(expectedMove, bestMove.Move, "Wrong best move at depth " + depth);
AssertWinner(bestMove.Score, Occupied.PlayerX);
}
private MinimaxResult MinimaxStep(BoardData p_board, Players p_player, int p_currentDepth)
{
GameResults t_gameResult = p_board.GetGameResult();
if (t_gameResult != GameResults.Unfinished)
{
int t_score = t_gameResult == GameResults.Win ? MAX_SCORE : -MAX_SCORE;
return(new MinimaxResult(t_score, null));
}
else if (p_currentDepth > MAX_DEPTH)
{
return(m_boardEvaluator.EvaluateBoard(p_board, p_player));
}
Move t_bestMove = null;
int t_bestScore = 0;
if (p_board.CurrentPlayer == Players.Human)
{
t_bestScore = -INFINITE;
}
else
{
t_bestScore = INFINITE;
}
List <Move> t_moves = new List <Move>();
p_board.GetMoves(t_moves);
foreach (Move t_move in t_moves)
{
BoardData t_newBoard = p_board.GetNewBoard(t_move);
MinimaxResult t_result = MinimaxStep(t_newBoard, p_player, p_currentDepth + 1);
if (p_board.CurrentPlayer == Players.Human)
{
if (t_bestScore < t_result.Score)
{
t_bestScore = t_result.Score;
t_bestMove = t_move;
}
}
else
{
if (t_result.Score < t_bestScore)
{
t_bestScore = t_result.Score;
t_bestMove = t_move;
}
}
}
return(new MinimaxResult(t_bestScore, t_bestMove));
}
public void GoodMoveAtLevel3()
{
HexBoard board = new HexBoard(6);
PlayToWinInThreeMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult bestMove = minimax.DoMinimax(3, true);
Location win = new Location(1, 3);
Assert.AreEqual(win, bestMove.Move, "Wrong play location");
}
/// <summary>
/// Recursively search for the best move for the given board
/// </summary>
/// <param name="depth">How many recursive iterations you want to take(each iteration is 1 turn of 1 of the players, so steps ahead is depth/2</param>
/// <param name="tiles">The Tile to iterate over</param>
/// <param name="initialSequence">Initial sequence of moves, which is used as state to know what sequence </param>
/// <param name="priority"></param>
/// <param name="max"></param>
/// <param name="currentPlayer"></param>
/// <param name="enemyPlayer"></param>
/// <returns></returns>
public MinimaxResult GetBestTurn(BoardTileCollection tiles, IPlayer currentPlayer)
{
IPlayer enemyPlayer = this.Game.GetEnemyPlayer(currentPlayer);
var results = new List <MinimaxResult>();
//get all possible initial moves for the player
var checkerMovePairs = currentPlayer.GetAllPossibleMoves(Game, enemyPlayer, tiles);
//loop variables
Parallel.ForEach(checkerMovePairs, (pair) => {
//foreach(var pair in checkerMovePairs) { //for each checker
List <MoveSequence> possibleSequences = null;
Turn turn = pair.Value;
foreach (var move in turn.Moves) //for each initial move of the checker
{
if (move is AttackMove attMove)
{
//all possible followup move sequences
possibleSequences = GetPossibleMoveSequences(turn, attMove);
}
else if (move is WalkMove)
{
possibleSequences = new List <MoveSequence> {
new MoveSequence(turn, new List <Move> {
move
})
};
}
//Parallel.ForEach(possibleSequences, (sequence) => { // Not useful, its max 2 moves
foreach (var sequence in possibleSequences)
{
BoardTileCollection clonedTiles = (BoardTileCollection)tiles.Clone();
float prio = sequence.Moves[0].Priority;
foreach (var mov in sequence.Moves)
{
Board.TakeMove(clonedTiles, mov);
}
//now we need to call the same method from the enemy perception again
var sequenceValue = GetBestMoveSequence(this.MaxDepth, clonedTiles, prio, enemyPlayer, currentPlayer);
var result = new MinimaxResult(sequence.Moves, sequence.Turn, sequenceValue);
results.Add(result);
}
//});
}
});
//}
return(ChooseBestResult(results));
}
public void TestCalculateMove2MinimaxPlayerY()
{
HexBoard board = new HexBoard(3);
PlayTwoMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult secondPlayerResult = minimax.DoMinimax(2, false);
Location expectedPlay = new Location(0, 2);
Assert.AreEqual(expectedPlay, secondPlayerResult.Move, "Wrong play location");
Assert.IsFalse(MoveScoreConverter.IsWin(secondPlayerResult.Score));
}
public void TestCalculateMove3PlayerX()
{
HexBoard board = new HexBoard(5);
PlayFourMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult firstPlayerResult = minimax.DoMinimax(4, true);
Location firstPlayerExpectedMove = new Location(2, 1);
Assert.AreEqual(firstPlayerExpectedMove, firstPlayerResult.Move, "Wrong first player location");
}
public void TestCalculateMoveLookahead1Player1()
{
HexBoard board = new HexBoard(3);
PlayFourMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult firstPlayerResult = minimax.DoMinimax(1, true);
Location expectedMove = new Location(1, 1);
Assert.AreEqual(expectedMove, firstPlayerResult.Move, "playerOneBestMove");
AssertWinner(firstPlayerResult.Score, Occupied.PlayerX);
}
private static void TestBestMove(HexGame game, int level, Location expectedBestMove)
{
Minimax hexPlayer = new Minimax(game.Board, game.GoodMoves, new CandidateMovesAll());
MinimaxResult bestMove = hexPlayer.DoMinimax(level, true);
// test the location of the move
Assert.AreEqual(expectedBestMove, bestMove.Move, "Wrong move at level " + level);
// test the expected score
if (level >= 3)
{
Assert.AreEqual(Occupied.PlayerX, MoveScoreConverter.Winner(bestMove.Score));
}
}
public void TestCalculateMoveLookahead1Player2()
{
HexBoard board = new HexBoard(3);
PlayFourMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult secondPlayerResult = minimax.DoMinimax(1, false);
Location expectedMove = new Location(1, 1);
Assert.AreEqual(expectedMove, secondPlayerResult.Move, "playerTwoBestMove");
AssertWinner(secondPlayerResult.Score, Occupied.PlayerY);
}
public void TestCalculateMove3MinimaxPlayerX()
{
HexBoard board = new HexBoard(3);
PlayTwoMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult firstPlayerResult = minimax.DoMinimax(3, true);
Location bestMoveLocation = firstPlayerResult.Move;
int moveScore = firstPlayerResult.Score;
Location exectedWin = new Location(0, 2);
Assert.AreEqual(exectedWin, bestMoveLocation, "Wrong win location");
AssertWinner(moveScore, Occupied.PlayerX);
}
public void TestCalculateMove3MinimaxPlayerY()
{
HexBoard board = new HexBoard(3);
PlayTwoMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult secondPlayerResult = minimax.DoMinimax(3, false);
Location secondPlayerMoveLocation = secondPlayerResult.Move;
int moveScore = secondPlayerResult.Score;
Location exectedWin = new Location(0, 2);
Assert.AreEqual(exectedWin, secondPlayerMoveLocation, "Wrong second player location");
AssertWinner(moveScore, Occupied.PlayerY);
}
public void RightMoveAtLevel5PlayerY()
{
HexBoard board = new HexBoard(6);
PlayToWinInThreeMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
MinimaxResult bestMove = minimax.DoMinimax(5, false);
List <Location> playerYWinningLocations = new List <Location>
{
new Location(1, 3),
new Location(2, 2)
};
Assert.IsTrue(playerYWinningLocations.Contains(bestMove.Move), "Wrong play location");
}
public void TestMinimax3()
{
HexBoard board = new HexBoard(5);
Minimax minimax = MakeMinimaxForBoard(board);
/*
* on a 5 * 5 board, red(playerx) has 3, 0 and 1, 4
* needs to play 2,2 to win - should know this at look ahead 5
*/
board.PlayMove(3, 0, true);
board.PlayMove(1, 4, true);
MinimaxResult bestMove = minimax.DoMinimax(5, true);
Location expectedMove = new Location(2, 2);
Assert.IsTrue(MoveScoreConverter.IsWin(bestMove.Score), "No win " + bestMove.Score);
Assert.AreEqual(expectedMove, bestMove.Move, "Wrong expected move");
}
public void TestMinimax4()
{
HexBoard board = new HexBoard(5);
Minimax minimax = MakeMinimaxForBoard(board);
/*
* on a 5 * 5 board, red(playerx) has 3, 0 and 1, 4 and 2,2
* PlayerX has won, even if PlayerY goes next
* should know this at look ahead 5
*/
board.PlayMove(3, 0, true);
board.PlayMove(1, 4, true);
board.PlayMove(2, 2, true);
MinimaxResult bestMove = minimax.DoMinimax(4, false);
AssertWinner(bestMove.Score, Occupied.PlayerX);
}
private Location GetBestMove(MinimaxResult playResult)
{
Location result = playResult.Move;
int moveScore = playResult.Score;
this.IsGameWon = MoveScoreConverter.IsWin(moveScore) && MoveScoreConverter.WinDepth(moveScore) == 1;
Occupied opponent = (!this.hexGame.PlayerX).ToPlayer();
bool losingMove = MoveScoreConverter.Winner(playResult.Score) == opponent;
if (losingMove)
{
Location losingLocation = this.MakeLosingMove();
if (losingLocation != Location.Null)
{
result = losingLocation;
}
}
return(result);
}
public void TestCalculateMove3PlayerY()
{
HexBoard board = new HexBoard(5);
PlayFourMoves(board);
Minimax minimax = MakeMinimaxForBoard(board);
// test score at this point
PathLengthLoop pathLength = new PathLengthLoop(board);
int playerScore = pathLength.PlayerScore(true);
Assert.AreEqual(3, playerScore);
playerScore = pathLength.PlayerScore(false);
Assert.AreEqual(3, playerScore);
MinimaxResult secondPlayerResult = minimax.DoMinimax(4, false);
Location secondPlayerExpectedMove = new Location(1, 2);
Assert.AreEqual(secondPlayerExpectedMove, secondPlayerResult.Move, "Wrong second player location");
}
/// <summary>
/// Recursively search for the best move for the given board
/// </summary>
/// <param name="depth">How many recursive iterations you want to take(each iteration is 1 turn of 1 of the players, so steps ahead is depth/2</param>
/// <param name="tiles">The Tile to iterate over</param>
/// <param name="initialSequence">Initial sequence of moves, which is used as state to know what sequence </param>
/// <param name="priority"></param>
/// <param name="max"></param>
/// <param name="currentPlayer"></param>
/// <param name="enemyPlayer"></param>
/// <returns></returns>
public MinimaxResult GetBestTurn(BoardTileCollection tiles, IPlayer currentPlayer)
{
IPlayer enemyPlayer = this.Game.GetEnemyPlayer(currentPlayer);
var results = new List <MinimaxResult>();
//get all possible initial moves for the player
var checkerMovePairs = currentPlayer.GetAllPossibleMoves(Game, enemyPlayer, tiles);
//loop variables
List <MoveSequence> possibleSequences = null;
foreach (var pair in checkerMovePairs) //for each checker
{
Turn turn = pair.Value;
foreach (var move in turn.Moves) //for each initial move of the checker
{
if (move is AttackMove attMove)
{
//all possible followup move sequences
possibleSequences = GetPossibleMoveSequences(turn, attMove);
}
else if (move is WalkMove)
{
possibleSequences = new List <MoveSequence> {
new MoveSequence(turn, new List <Move> {
move
})
};
}
foreach (var sequence in possibleSequences)
{
BoardTileCollection clonedTiles = (BoardTileCollection)tiles.Clone();
float prio = sequence.Moves[0].Priority;
foreach (var mov in sequence.Moves)
{
Board.TakeMove(clonedTiles, mov);
}
//now we need to call the same method from the enemy perception again
var sequenceValue = GetBestMoveSequence(this.MaxDepth, clonedTiles, prio, enemyPlayer, currentPlayer);
var result = new MinimaxResult(sequence.Moves, sequence.Turn, sequenceValue);
results.Add(result);
}
}
}
#if DEBUG
var str = "";
foreach (var result in results)
{
str += $"move: {result.Moves.First().StartLocation} => {result.Moves.Last().EndLocation}, value:{result.TurnValue}\n";
}
Console.WriteLine($"Turn: {this.Game.Turn}");
Console.WriteLine(str);
#endif
if (results.Count() == 0)
{
return(null);
}
IEnumerable <MinimaxResult> bestResults = ((this.MaxDepth & 0b1) == 0b1) ? results.Where(res => res.TurnValue == results.Max(r => r.TurnValue))
: results.Where(res => res.TurnValue == results.Min(r => r.TurnValue));
var random = new Random();
var ind = random.Next(0, bestResults.Count());
var chosenResult = bestResults.ElementAtOrDefault(ind);
return(chosenResult);
}
/// <summary>
/// private recursive worker - does the minimax algorithm
/// </summary>
/// <param name="lookahead">the current ply, counts down to zero</param>
/// <param name="stateBoard">the current board</param>
/// <param name="isPlayerX">player X or player Y</param>
/// <param name="alpha">alpha value used in alpha-beta pruning</param>
/// <param name="beta">beta value used in alpha-beta pruning</param>
/// <returns>the score of the board and best move location</returns>
private MinimaxResult ScoreBoard(
int lookahead,
HexBoard stateBoard,
bool isPlayerX,
int alpha,
int beta)
{
this.CountBoards++;
MinimaxResult bestResult = null;
Location cutoffMove = Location.Null;
var possibleMoves = this.candidateMovesFinder.CandidateMoves(stateBoard, lookahead);
foreach (Location move in possibleMoves)
{
// end on null loc
if (move.IsNull())
{
break;
}
if (this.GenerateDebugData)
{
this.AddDebugDataItem(lookahead, move, isPlayerX, alpha, beta);
}
// make a speculative board, like the current, but with this cell played
HexBoard testBoard = this.boardCache.GetBoard();
testBoard.CopyStateFrom(stateBoard);
testBoard.PlayMove(move, isPlayerX);
MinimaxResult moveScore;
PathLengthBase staticAnalysis = this.pathLengthFactory.CreatePathLength(testBoard);
int situationScore = staticAnalysis.SituationScore();
if (lookahead <= 1)
{
// we have reached the limits of lookahead - return the situation score
moveScore = new MinimaxResult(situationScore);
}
else if (MoveScoreConverter.IsWin(situationScore))
{
// stop - someone has won
moveScore = new MinimaxResult(situationScore);
}
else
{
// recurse
moveScore = this.ScoreBoard(lookahead - 1, testBoard, !isPlayerX, beta, alpha);
moveScore.MoveWins();
}
moveScore.Move = move;
this.boardCache.Release(testBoard);
// higher scores are good for player x, lower scores for player y
if (bestResult == null || MoveScoreConverter.IsBetterFor(moveScore.Score, bestResult.Score, isPlayerX))
{
bestResult = new MinimaxResult(move, moveScore);
}
// do the alpha-beta pruning
alpha = CheckAlpha(alpha, moveScore.Score, isPlayerX);
if (IsAlphaBetaCutoff(isPlayerX, alpha, beta))
{
cutoffMove = move;
bestResult.Score = alpha;
break;
}
// end a-b pruning
}
if (bestResult != null)
{
GoodMoves.AddGoodMove(lookahead, bestResult.Move);
}
if (cutoffMove != Location.Null)
{
GoodMoves.AddGoodMove(lookahead, cutoffMove);
}
return(bestResult);
}
