private void getOptimalCell(byte i_PlayerIndex, out Board.Cell o_ResultMove)
{
const byte k_FirstHumanMoveIndex = 0;
const byte k_LastUnblockingEmptyCell = 0;
Random rnd = new Random();
Board.Cell targetedCell = this.gameLogic.Players[GetOtherPlayerIndex(i_PlayerIndex)].m_MovesList[k_FirstHumanMoveIndex];
List <Board.Cell> unblockingEmptyCells = this.getUnblockingEmptyCells(targetedCell);
if (unblockingEmptyCells.Count != k_LastUnblockingEmptyCell)
{
o_ResultMove = unblockingEmptyCells[rnd.Next(unblockingEmptyCells.Count)];
if (!this.gameLogic.checkIfPlayerLost(o_ResultMove, i_PlayerIndex))
{
unblockingEmptyCells.Remove(o_ResultMove);
}
}
else
{
List <Board.Cell> freeCellsInBoard = this.getFreeCellsInBoard();
o_ResultMove = freeCellsInBoard[rnd.Next(freeCellsInBoard.Count)];
while (this.gameLogic.checkIfPlayerLost(o_ResultMove, i_PlayerIndex))
{
const int k_LastComputerOptionalCell = 1;
if (freeCellsInBoard.Count == k_LastComputerOptionalCell)
{
break;
}
freeCellsInBoard.Remove(o_ResultMove);
o_ResultMove = freeCellsInBoard[rnd.Next(freeCellsInBoard.Count)];
}
}
}
/// <summary>
/// Set the text (Nought or Cross) for a button, and then
/// disable it so user cannot click it again during this game.
/// </summary>
/// <param name="button">Button to set</param>
/// <param name="cell">Nought, Cross or Empty</param>
private void SetButtonCell(Button button, Board.Cell cell)
{
switch (cell)
{
case Board.Cell.Computer:
{
button.Text = Board.CellToString(cell);
button.Enabled = false;
break;
}
case Board.Cell.Human:
{
button.Text = Board.CellToString(cell);
button.Enabled = false; break;
}
case Board.Cell.Empty:
{
button.Text = Board.CellToString(cell);
button.Enabled = true;
break;
}
}
}
private bool checkDiagonalLose(Board.Cell i_LastMove, byte i_PlayerIndex, eSign i_PlayerSign)
{
bool minorDiagonalLoseFlag = true;
bool majorDiagonalLoseFlag = true;
for (byte colRowIndex = 0; colRowIndex < this.Board.BoardSize; colRowIndex++)
{
if (i_LastMove != this.Board[(byte)(this.m_BoardSize - colRowIndex - 1), colRowIndex])
{
if (minorDiagonalLoseFlag && this.Board[(byte)(this.Board.BoardSize - colRowIndex - 1), colRowIndex].m_CellSign != i_PlayerSign)
{
minorDiagonalLoseFlag = false;
}
}
if (i_LastMove != this.Board[colRowIndex, colRowIndex])
{
if (majorDiagonalLoseFlag && this.Board[colRowIndex, colRowIndex].m_CellSign != i_PlayerSign)
{
majorDiagonalLoseFlag = false;
}
}
}
bool minorOrMajorDiagonalLose = minorDiagonalLoseFlag || majorDiagonalLoseFlag;
if (minorOrMajorDiagonalLose)
{
this.Players[i_PlayerIndex].RoundStatus = minorDiagonalLoseFlag ? eRoundStatus.MinorDiagonalLose : eRoundStatus.MajorDiagonalLose;
this.Players[GetOtherPlayerIndex(i_PlayerIndex)].RoundStatus = eRoundStatus.Win;
}
return(minorOrMajorDiagonalLose);
}
/// <summary>
/// Calculate the node
/// </summary>
/// <param name="board">Current board state</param>
/// <param name="currentPosition">Position in board to set</param>
/// <param name="currentMove">Current move (either Computer or Human)</param>
/// <param name="depth">Current depth. Used for choosing earliest winning/losing move</param>
public MiniMaxNode(Board board, int currentPosition, Board.Cell currentMove, int depth)
{
// Create the child nodes list
this.ChildNodes = new List <MiniMaxNode>();
// Save the index to the cell we are updating. This way we always know what move
// this node corresponds to
this.UpdatedCellIndex = currentPosition;
// Set the cell to Computer/Human
board.Cells[this.UpdatedCellIndex] = currentMove;
if (board.GetState() == Board.State.ComputerWins)
{
// If Computer wins, give it a high score, but deduct the current depth
// (So that quick wins have higher scores than lengthy wins)
this.Score = 10 - depth;
}
else if (board.GetState() == Board.State.HumanWins)
{
// If Human wins, give it a low score, but add the current depth
// (So that quick loses have lower scores than lengthy loses)
this.Score = -10 + depth;
}
else if (board.GetState() == Board.State.Draw)
{
// If it's a draw, just set to neutral
this.Score = 0;
}
else
{
// Invert the player
var nextMove = currentMove == Board.Cell.Computer ? Board.Cell.Human : Board.Cell.Computer;
for (var i = 0; i < Board.BoardSize; i++)
{
// For each empty cell
if (board.Cells[i] == Board.Cell.Empty)
{
// Clone the board
var childBoard = board.Clone();
// Calculate child moves
var miniMaxNode = new MiniMaxNode(childBoard, i, nextMove, depth + 1);
ChildNodes.Add(miniMaxNode);
}
}
if (currentMove == Board.Cell.Computer)
{
// Since this isn't a terminal node, give the current node the best score
// amongst the child nodes..
this.Score = this.ChildNodes.OrderBy(n => n.Score).First().Score;
}
else
{
// ..or for Human moves, give it the worst score amongst the children
this.Score = this.ChildNodes.OrderBy(n => n.Score).Last().Score;
}
}
}
private bool checkIfPlayerLost(Board.Cell i_LastMove, byte i_PlayerIndex)
{
eSign playerSign = this.Players[i_PlayerIndex].Sign;
bool gameFinishedFlag = this.checkRowOrColLose(i_LastMove, i_PlayerIndex, playerSign);
if (!gameFinishedFlag && this.isCellOnDiagonal(i_LastMove))
{
gameFinishedFlag = this.checkDiagonalLose(i_LastMove, i_PlayerIndex, playerSign);
}
return(gameFinishedFlag);
}
internal void HandleComputerMove()
{
this.m_CurrentNumOfMoves++;
Board.Cell computerMove = this.r_GameLogic.GetAIMove(this.m_PlayerIndexTurn);
this.r_GameLogic.RegisterMove(computerMove, this.m_PlayerIndexTurn);
this.MarkCellWithComputerSign(computerMove, this.m_PlayerIndexTurn);
this.m_IsGameFinished = this.r_GameLogic.CheckEndGame(computerMove, this.m_CurrentNumOfMoves, this.m_PlayerIndexTurn);
this.m_PlayerIndexTurn = GameLogic.GetOtherPlayerIndex(this.m_PlayerIndexTurn);
if (this.m_IsGameFinished)
{
this.showResults(this.m_PlayerIndexTurn);
this.resetRound();
}
this.boldPlayer(k_Player1Index);
}
internal bool CheckEndGame(Board.Cell i_CurrentMove, byte i_CurrentNumOfMoves, byte i_PlayerIndex)
{
bool isGameFinished = false;
if (this.checkIfPlayerLost(i_CurrentMove, i_PlayerIndex))
{
isGameFinished = true;
this.Players[GetOtherPlayerIndex(i_PlayerIndex)].Score++;
}
if (!isGameFinished)
{
isGameFinished = this.handleFullBoard(i_CurrentNumOfMoves);
}
return(isGameFinished);
}
internal void RegisterMove(Board.Cell i_CurrentMove, byte i_PlayerIndex)
{
this.Board[i_CurrentMove] = i_CurrentMove;
this.Board[i_CurrentMove].m_CellSign = this.Players[i_PlayerIndex].Sign;
if (this.Players[i_PlayerIndex].PlayerType == ePlayerType.Human)
{
this.Players[i_PlayerIndex].m_MovesList.Add(i_CurrentMove);
}
CellChosenEventArgs e =
new CellChosenEventArgs
{
m_CellSign = i_CurrentMove.m_CellSign,
m_CellIndex = Board.GetCellIndexInBoard(i_CurrentMove)
};
OnCellChosen(e);
}
internal void MarkCellWithComputerSign(Board.Cell i_ComputerMove, byte i_PlayerIndex)
{
bool found = false;
string cellCoordinates = $"{i_ComputerMove.m_CellRow},{i_ComputerMove.m_CellCol}";
while (!found)
{
foreach (Button cellButton in this.r_CellButtons)
{
if (cellButton.Name == cellCoordinates)
{
found = true;
this.changeCellButtonAppearance(cellButton, i_ComputerMove.m_CellSign);
break;
}
}
}
}
private List <Board.Cell> getUnblockingEmptyCells(Board.Cell i_TargetedCell)
{
List <Board.Cell> optionalCells = new List <Board.Cell>();
for (byte rowIndex = 0; rowIndex < this.gameLogic.m_BoardSize; rowIndex++)
{
for (byte colIndex = 0; colIndex < this.gameLogic.m_BoardSize; colIndex++)
{
if (this.gameLogic.Board[rowIndex, colIndex].m_CellSign == eSign.Empty)
{
if (rowIndex != i_TargetedCell.m_CellRow &&
colIndex != i_TargetedCell.m_CellCol &&
!this.gameLogic.isCellOnDiagonal(this.gameLogic.Board[rowIndex, colIndex]))
{
optionalCells.Add(this.gameLogic.Board[rowIndex, colIndex]);
}
}
}
}
return(optionalCells);
}
private bool checkRowOrColLose(Board.Cell i_LastMove, byte i_PlayerIndex, eSign i_PlayerSign)
{
bool rowLoseFlag = true;
bool colLoseFlag = true;
byte currentCol = i_LastMove.m_CellCol;
byte currentRow = i_LastMove.m_CellRow;
for (byte colRowIndex = 0; colRowIndex < this.Board.BoardSize && (colLoseFlag || rowLoseFlag); colRowIndex++)
{
if (i_LastMove != this.Board[colRowIndex, currentCol])
{
if (colLoseFlag && this.Board[colRowIndex, currentCol].m_CellSign != i_PlayerSign)
{
colLoseFlag = false;
}
}
if (i_LastMove != this.Board[currentRow, colRowIndex])
{
if (rowLoseFlag && this.Board[currentRow, colRowIndex].m_CellSign != i_PlayerSign)
{
rowLoseFlag = false;
}
}
}
bool rowOrColLoseFlag = rowLoseFlag || colLoseFlag;
if (rowOrColLoseFlag)
{
this.Players[i_PlayerIndex].RoundStatus = rowLoseFlag ? eRoundStatus.RowLose : eRoundStatus.ColLose;
this.Players[GetOtherPlayerIndex(i_PlayerIndex)].RoundStatus = eRoundStatus.Win;
}
return(rowOrColLoseFlag);
}
private void getRandomCell(out Board.Cell o_ResultMove)
{
Random rnd = new Random();
o_ResultMove = new Board.Cell((byte)rnd.Next(this.gameLogic.m_BoardSize), (byte)rnd.Next(this.gameLogic.m_BoardSize));
}
internal bool CheckCellLegality(Board.Cell o_ResultMove)
{
return(this.Board.IsCellInRange(o_ResultMove) && this.Board.IsCellUsed(o_ResultMove));
}
private bool isCellOnDiagonal(Board.Cell i_LastMove)
{
return(i_LastMove.m_CellRow == i_LastMove.m_CellCol ||
i_LastMove.m_CellRow + i_LastMove.m_CellCol + 1 == this.Board.BoardSize);
}