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));
}
/*
* BoardsScores explanation:
*
* BoardScores are checked from the highest score to the lowest, if a
* board fits in a BoardScores score, the that score is returned and
* there is no further checking.
* What a BoardScores score consists of is explained below:
*
* TERMINAL: board with two CHECK where the enemy will lose whatever move
* he does.
* X · O
* · O ·
* X · X
*
* TRIPLETRAP: board where by placing one more tile there would be three CHECK
* X · @ @ = By placing another X here there would be three CHECK
* · · ·
* X O ·
*
* DOUBLETRAP: same as before, but by placing the said tile there would be two CHECK
* · · @ @ = By placing another X here there would be three CHECK
* · · ·
* X O X
*
* EASYTRAP: DOUBLETRAP that is at the same time a CHECK
* · · ·
* · O ·
* X · X
*
* CHECK: board where by placing one more tile the game would be a win
* O · ·
* X X ·
* O · ·
*
* CORNER: board where the tile is in a corner
* X · ·
* · · ·
* · · ·
*/
public MinimaxResult EvaluateBoard(BoardData p_board, Players p_player)
{
int t_score = 0;
Tiles t_currentPlayerTile = p_board.HumanTile;
if (Players.AI == p_player)
{
t_currentPlayerTile = p_board.HumanTile ^ (Tiles)1;
}
GameResults t_gameResult = p_board.GetGameResult();
if (t_gameResult == GameResults.Tie)
{
t_score = 0;
}
else if (t_gameResult == GameResults.Unfinished)
{
t_score = ScoreUnfinishedBoard(p_board, t_currentPlayerTile);
}
else
{
if (t_gameResult == GameResults.Win)
{
t_score = Minimax.MAX_SCORE;
}
else
{
t_score = -Minimax.MAX_SCORE;
}
}
if (p_player == Players.AI)
{
t_score *= -1;
}
return(new MinimaxResult(t_score, null));
}
