/// <summary> /// Undoes the last move, restoring the game to its state before the move was applied. /// </summary> public void UndoLastMove() { OthelloMove m = MoveHistory[MoveHistory.Count - 1] as OthelloMove; // Note: there is a bug in this code. if (!m.IsPass) { // Reset the board at the move's position. mBoard[m.Position.Row, m.Position.Col] = 0; Value += mCurrentPlayer; Weight += mCurrentPlayer * mWeights[m.Position.Row, m.Position.Col]; // Iterate through the move's recorded flipsets. foreach (var flipSet in m.FlipSets) { BoardPosition pos = m.Position; // For each flipset, walk along the flipset's direction resetting pieces. for (int i = 1; i <= flipSet.Count; i++) { pos = pos.Translate(flipSet.RowDelta, flipSet.ColDelta); mBoard[pos.Row, pos.Col] = (sbyte)mCurrentPlayer; Value += 2 * mCurrentPlayer; Weight += 2 * mCurrentPlayer * mWeights[pos.Row, pos.Col]; } } // Check to see if the second-to-last move was a pass; if so, set PassCount. if (MoveHistory.Count > 1 && (MoveHistory[MoveHistory.Count - 2] as OthelloMove).IsPass) { PassCount = 1; } } else { PassCount--; } // Reset the remaining game state. mCurrentPlayer = -mCurrentPlayer; MoveHistory.RemoveAt(MoveHistory.Count - 1); }
/// <summary> /// Applies the given move to the board state. /// </summary> /// <param name="m">a move that is assumed to be valid</param> public void ApplyMove(IGameMove move) { OthelloMove m = move as OthelloMove; // If the move is a pass, then we do very little. if (m.IsPass) { PassCount++; } else { PassCount = 0; // Otherwise update the board at the move's position with the current player. mBoard[m.Position.Row, m.Position.Col] = (sbyte)mCurrentPlayer; Value += mCurrentPlayer; // Iterate through all 8 directions radially from the move's position. for (int rDelta = -1; rDelta <= 1; rDelta++) { for (int cDelta = -1; cDelta <= 1; cDelta++) { if (rDelta == 0 && cDelta == 0) { continue; } // Repeatedly move in the selected direction, as long as we find "enemy" squares. BoardPosition newPos = m.Position; int steps = 0; do { newPos = newPos.Translate(rDelta, cDelta); steps++; } while (PositionInBounds(newPos) && PositionIsEnemy(newPos, mCurrentPlayer)); // This is a valid direction of flips if we moved at least 2 squares, and ended in bounds and on a // "friendly" square. if (steps > 1 && PositionInBounds(newPos) && mBoard[newPos.Row, newPos.Col] == mCurrentPlayer) { // Record this direction in the move's flipsets so the move can be undone. m.AddFlipSet( new OthelloMove.FlipSet() { RowDelta = rDelta, ColDelta = cDelta, Count = steps - 1 }); // The FlipSet constructor takes no parameters; this syntax allows us to construct a FlipSet // and initialize many of its properties in one expression. // Repeatedly walk back the way we came, updating the board with the current player's piece. newPos = newPos.Translate(-rDelta, -cDelta); while (steps > 1) { mBoard[newPos.Row, newPos.Col] = (sbyte)mCurrentPlayer; Value += 2 * mCurrentPlayer; newPos = newPos.Translate(-rDelta, -cDelta); steps--; } } } } } // Update the rest of the board state. mCurrentPlayer = -mCurrentPlayer; MoveHistory.Add(m); }
/// <summary> /// Returns true if the two objects have the same position. /// </summary> public bool Equals(IGameMove obj) { OthelloMove other = obj as OthelloMove; return(other.Position.Row == this.Position.Row && other.Position.Col == this.Position.Col); }