private Boards CopyAndMove(Boards boards, Move move)
{
Boards newBoards = new Boards(boards);
newBoards.SetTile_Small(move);
if (newBoards.GetWinner(move.board) != Game.EMPTY)
newBoards.SetTile_Big(move.board);
newBoards.lastmove = newBoards.GetWinner(move.tile)
== Game.EMPTY ? move.tile : -1;
newBoards.FillMoves();
return newBoards;
}
private int NegaMax(Boards boards, int depth, int alpha, int beta)
{
int bigBoardRating = boards.GetWinner(9);
if (bigBoardRating == Game.DRAW)
return 0;
if (bigBoardRating == Game.X)
return 100000 * (boards.turn ? -1 : 1);
if (bigBoardRating == Game.O)
return -100000 * (boards.turn ? -1 : 1);
if (depth == 0)
return Eval(boards) * (boards.turn ? -1 : 1);
int best = -1000000;
foreach (Move m in boards.moves)
{
int score = -NegaMax(CopyAndMove(boards, m),
depth - 1, -beta, -alpha);
if (score > best)
best = score;
if (best > alpha)
alpha = best;
if (alpha >= beta)
return alpha;
}
return best;
}