/// <summary>
/// returns a move that will make the AI one step from winning (not a trap)
/// </summary>
/// <param name="gl">The <seealso cref="GameLogic"/> of the game the ai playing.</param>
/// <returns></returns>
private Position Ahead(GameLogic gl)
{
var ex = new GameLogic(gl);
var a = ex.AllFreeSpaces();
for (int i = 0; i < a.Length; i++)
{
PutMe(ex, a[i]);
if (EasyWin(ex).row != -1)
{
return(a[i]);
}
ex.Undo();
}
return(new Position(-1, -1));
}
/// <summary>
/// Returns in how many ways can the AI win in it next turn.
/// </summary>
/// <param name="gl">The game the AI is playing</param>
/// <returns></returns>
private int WinningWays(GameLogic gl)
{
var ex = new GameLogic(gl);
var pos = ex.AllFreeSpaces();
int result = 0, freeSpaces = pos.Length;
for (int i = 0; i < freeSpaces; i++)
{
PutMe(ex, pos[i]);
if (AmIWon(ex))
{
result++;
}
ex.Undo();
}
return(result);
}
/// <summary>
/// Tries to do tricks to elevate the AI situation.
/// </summary>
/// <param name="gl"></param>
/// <returns></returns>
private Position Tricks(GameLogic gl)
{
var ex = new GameLogic(gl);
Stack <Position> corners = new Stack <Position>();
Stack <Position> sides = new Stack <Position>();
if (ex.History.Count == 1)
{
if (HasInCorner(ex, him, out corners))
{
return(new Position(1, 1));
}
if (HasInSides(ex, him, out sides))
{
return(new Position(1, 1));
}
if (ex.board.board[1, 1].player == him)
{
return(new Position(0, 0));
}
}
if (Ahead(ex).row != -1)
{
return(Ahead(ex));
}
var pos = ex.AllFreeSpaces();
Position best = pos[0];
int best_int = 0;
for (int i = 0; i < pos.Length; i++)
{
PutMe(ex, pos[i]);
if (WinningWays(ex) > best_int)
{
best_int = WinningWays(ex);
best = pos[i];
}
ex.Undo();
}
return(best);
return(new Position(-1, -1));
}
/// <summary>
/// returns the position in which its an immidate win for the player.
/// </summary>
/// <param name="gl">The <seealso cref="GameLogic"/> of the game the ai playing.</param>
/// <returns></returns>
private Position OEasyWin(GameLogic gl)
{
GameLogic ex = new GameLogic(gl);
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if (PutHim(ex, new Position(i, j)))
{
if (!AmIWon(ex) && !ex.IsDraw())
{
return(new Position(i, j));
}
else
{
ex.Undo();
}
}
}
}
return(new Position(-1, -1));
}
/// <summary>
/// return the positin which x will win if put there or -1,-1 if there's no such position
/// </summary>
/// <param name="gl">game logic of the game (will not affect the game)</param>
/// <returns></returns>
private Position MustPut(GameLogic gl)
{
GameLogic ex = new GameLogic(gl);
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if (PutHim(ex, new Position(i, j)))
{
if (DoHimWon(ex))
{
return(new Position(i, j));
}
else
{
ex.Undo();
}
}
}
}
return(new Position(-1, -1));
}