private int Minimax(int _depth, int _value, bool _IsMainPlayer, GameStage _stage, int _alpha, int _beta, PlayerName _mainPlayer)
{
if (_depth <= 0)
{
return(_value);
}
if (_IsMainPlayer)
{
int best = MIN_VALUE;
for (int i = 0; i < _stage.PosiblePosition.Count; i++)
{
var nextStage = _stage.Clone();
nextStage.SelectPosition(_stage.PosiblePosition[i]);
var wonPlayer = nextStage.CheckWonPlayer();
var reward = _mainPlayer == wonPlayer ? 2 : 1;
_value += wonPlayer != PlayerName.None ? reward : 0;
nextStage.SetNextPlayer();
int value = Minimax(_depth - 1, _value, false, _stage, _alpha, _beta, _mainPlayer);
best = Math.Max(best, value);
_alpha = Math.Max(_alpha, best);
if (_beta <= _alpha)
{
break;
}
}
return(best);
}
else
{
int best = MAX_VALUE;
for (int i = 0; i < _stage.PosiblePosition.Count; i++)
{
var nextStage = _stage.Clone();
nextStage.SelectPosition(_stage.PosiblePosition[i]);
_value += nextStage.CheckWonPlayer() != PlayerName.None ? 1 : 0;
int value = Minimax(_depth - 1, _value, true, _stage, _alpha, _beta, _mainPlayer);
best = Math.Min(best, value);
_beta = Math.Min(_beta, best);
if (_beta <= _alpha)
{
break;
}
}
return(best);
}
}
// -------------------------------------------------------------------------------------
// Public Funtion
public override IObservable <Position> MakeDicision(GameStage _stage, GameTime _gameTime)
{
return(Observable.Create <Position>
(
_observer =>
{
var gameTime = Observable.Timer(TimeSpan.FromSeconds((int)_gameTime)).Subscribe(_ =>
{
_observer.OnNext(new Position(-1, -1));
_observer.OnCompleted();
});
var disposable = Observable.Timer(TimeSpan.FromSeconds(0.5f)).Subscribe(_ =>
{
var cloneStage = _stage.Clone();
_observer.OnNext(FindBestSolution(cloneStage));
_observer.OnCompleted();
});
return Disposable.Create(() =>
{
gameTime?.Dispose();
disposable?.Dispose();
});
}
));
}
// -------------------------------------------------------------------------------------
// Private Funtion
private Position FindBestSolution(GameStage _stage)
{
var isMinimax = _stage.Players[0] != _stage.CurrentTurn;
var bestList = new List <Position>();
bestList.Add(_stage.RandomPosition());
var bestValue = isMinimax ? MAX_VALUE : MIN_VALUE;
var bestPos = _stage.RandomPosition();
for (int i = 0; i < _stage.PosiblePosition.Count; i++)
{
var nextStage = _stage.Clone();
nextStage.SelectPosition(_stage.PosiblePosition[i]);
nextStage.SetNextPlayer();
var value = Minimax(3, 0, false, nextStage, MIN_VALUE, MAX_VALUE, _stage.CurrentTurn);
if (isMinimax)
{
if (bestValue > value)
{
bestList = new List <Position>();
bestValue = value;
bestPos = _stage.PosiblePosition[i];
bestList.Add(_stage.PosiblePosition[i]);
}
else if (bestValue == value)
{
bestList.Add(_stage.PosiblePosition[i]);
}
}
else
{
if (bestValue < value)
{
bestList = new List <Position>();
bestValue = value;
bestPos = _stage.PosiblePosition[i];
bestList.Add(_stage.PosiblePosition[i]);
}
else if (bestValue == value)
{
bestList.Add(_stage.PosiblePosition[i]);
}
}
}
return(bestList[UnityEngine.Random.Range(0, bestList.Count)]);
}