/// <summary> /// Undoes the last move, restoring the game to its state before the move was applied. /// </summary> public void UndoLastMove() { OthelloMove m = mMoveHistory.Last(); if (!m.IsPass) { // Reset the board at the move's position. SetPlayerAtPosition(m.Position, 0); mAdvantageValue += mCurrentPlayer; BoardWeight += mCurrentPlayer * mPositionWeights[m.Position.Row, m.Position.Col]; // Iterate through the move's recorded flipsets. foreach (var flipSet in mFlipSets.Last()) { BoardPosition pos = m.Position; // For each flipset, walk along the flipset's direction resetting pieces. for (int i = 0; i < flipSet.Count; i++) { pos = pos.Translate(flipSet.Direction); // At this moment, CurrentPlayer is actually the enemy of the move that // we are undoing, whose pieces we must restore. SetPlayerAtPosition(pos, CurrentPlayer); mAdvantageValue += 2 * mCurrentPlayer; BoardWeight += 2 * mCurrentPlayer * mPositionWeights[pos.Row, pos.Col]; } } // Check to see if the second-to-last move was a pass; if so, set PassCount. if (mMoveHistory.Count > 1 && mMoveHistory[mMoveHistory.Count - 2].IsPass) { PassCount = 1; } } else { PassCount--; } // Reset the remaining game state. SetAdvantage(); mCurrentPlayer = -mCurrentPlayer; mMoveHistory.RemoveAt(mMoveHistory.Count - 1); mFlipSets.RemoveAt(mFlipSets.Count - 1); }
public void ApplyMove(OthelloMove m) { if (m == null) { throw new ArgumentNullException(nameof(m)); } List <FlipSet> currentFlips = new List <FlipSet>(); m.Player = CurrentPlayer; // 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. SetPlayerAtPosition(m.Position, CurrentPlayer); mAdvantageValue += mCurrentPlayer; // Iterate through all 8 directions radially from the move's position. foreach (BoardDirection dir in BoardDirection.CardinalDirections) { // Repeatedly move in the selected direction, as long as we find "enemy" squares. BoardPosition newPos = m.Position; int steps = 0; do { newPos = newPos.Translate(dir); steps++; } while (PositionIsEnemy(newPos, CurrentPlayer)); // 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 && GetPlayerAtPosition(newPos) == CurrentPlayer) { // Record a FlipSet for this direction currentFlips.Add(new FlipSet(dir, (sbyte)(steps - 1))); var reverse = -dir; // Repeatedly walk back the way we came, updating the board with the current player's piece. do { newPos = newPos.Translate(reverse); SetPlayerAtPosition(newPos, CurrentPlayer); mAdvantageValue += 2 * mCurrentPlayer; steps--; }while (steps > 1); } } } // Update the rest of the board state. mCurrentPlayer = -mCurrentPlayer; SetAdvantage(); mMoveHistory.Add(m); mFlipSets.Add(currentFlips); }