/// <summary>
/// Method called when the game passes control to this player
/// </summary>
/// <param name="game">Game object that this player belongs to</param>
public override void PromptForMove(Game game)
{
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
Square bestSquare = null;
float bestValue = float.MinValue;
_playerOpponent = game.Players[0];
if (_playerOpponent == this)
{
_playerOpponent = game.Players[1];
}
Random rand = new Random();
int equalSquares = 0;
foreach (Square square in game.Board.Squares)
{
if (square.Owner == null)
{
square.Owner = this;
float curValue = AlphaBetaPrune(game, int.MinValue, int.MaxValue, false);
square.Owner = null;
if (bestSquare == null || curValue > bestValue)
{
bestValue = curValue;
bestSquare = square;
equalSquares = 0;
}
else if (curValue == bestValue)
{
equalSquares++;
if (rand.Next(0,equalSquares + 1) == 0)
{
bestValue = curValue;
bestSquare = square;
}
}
}
}
int curTurnTime = (int)stopwatch.ElapsedMilliseconds;
int turnTimeDiff = _minTurnTime - curTurnTime;
Move move = new Move(this, bestSquare);
Action playMove = () => game.PlayMove(move);
int sleepMs = Math.Max(0, turnTimeDiff);
// Ensure that the AI waits at least the minTurnTime before playing a move,
// making the AI seem more human-like in that it won't make all of its moves near instantaniously.
_timer = new Timer(PlayMoveAfterDelayCallback, playMove, sleepMs, Timeout.Infinite);
}