private UtilityGameMove GetMinUtilityMove(UtilityGameMove originalMove, UtilityGameMove nextMove)
{
if (originalMove.Utility <= nextMove.Utility)
{
return(originalMove);
}
return(nextMove);
}
private UtilityGameMove MinValue(GameState gs, int alpha, int beta, GameMove lastMove = null, int depth = 0)
{
//var lastMoveValue = lastMove != null ? $"{lastMove.Location}, ${((lastMove.GameSymbol == GameSymbol.Cross) ? "Cross" : "Naught")}" : "null";
//Console.WriteLine($"Min value is called. Alpha: {alpha}, Beta: {beta}, lastMove: {lastMoveValue}");
var terminalState = PlayerUtilities.GetTerminalState(gs, PlayerSymbol);
if (terminalState != PlayerUtilities.TerminalState.Incomplete)
{
if (lastMove == null)
{
throw new Exception("Cannot find best move, in terminal state but with no last move");
}
var utilityValue = GetUtilityOfTerminalState(terminalState);
return(new UtilityGameMove(lastMove.Location, lastMove.GameSymbol, utilityValue));
}
var moves = gs.GetMoves();
var v = new UtilityGameMove(moves.First().Location, moves.First().GameSymbol, Int32.MaxValue);
foreach (var move in moves)
{
var copiedGameState = gs.Clone() as GameState;
copiedGameState.ApplyMove(move);
var u = MaxValue(copiedGameState, alpha, beta, move, ++depth);
v = GetMinUtilityMove(v, u);
beta = Math.Min(beta, v.Utility);
if (alpha >= beta)
{
if (lastMove != null)
{
return(new UtilityGameMove(lastMove.Location, lastMove.GameSymbol, v.Utility));
}
return(v);
}
}
if (lastMove != null)
{
return(new UtilityGameMove(lastMove.Location, lastMove.GameSymbol, v.Utility));
}
return(v);
}
