private MaxScoreData GetMaxScorePositions(EBoardSelection [] boardData, EBoardSelection inputMark)
{
MaxScoreData playerMaxScore = new MaxScoreData();
playerMaxScore.Reset();
DebugPrint("GetMaxScorePositions inputMark = " + inputMark.ToString());
List <int> scoreList = new List <int>();
//First check if there is a potential winner with next move and calculate scores
for (int i = 0; i < MAX_NUM_MARKS; i++)
{
if (boardData [i] == EBoardSelection.E_Selection_None)
{
int score = CalculateScore(boardData, inputMark, i);
scoreList.Add(score);
if (score == WINNING_SCORE)
{
playerMaxScore.score = score;
playerMaxScore.positions = new List <int> ();
playerMaxScore.positions.Add(i);
break; // We have a clear winner so break from loop
}
else if (playerMaxScore.score != WINNING_SCORE &&
playerMaxScore.score < score)
{
//If the score is less then remove the old scores
if (playerMaxScore.score < score)
{
playerMaxScore.positions = null;
playerMaxScore.positions = new List <int> ();
}
playerMaxScore.score = score;
playerMaxScore.positions.Add(i);
}
else
{
//ignore the position
}
}
else
{
scoreList.Add(INVALID_SCORE);
}
}
string debugScores = "";
for (int i = 0; i < scoreList.Count; i++)
{
debugScores += scoreList[i];
debugScores += "\t";
}
DebugPrint("GetMaxScorePositions Scores = " + debugScores);
return(playerMaxScore);
}
public EBoardSelection EvaluateWin(EBoardSelection [] boardData, ref int [] winningPositions)
{
UnityEngine.Debug.Assert(boardData.Length == MAX_NUM_MARKS, "Number of marks on board cant exceed max");
EBoardSelection winner = EBoardSelection.E_Selection_None;
for (int i = 0; i < MathWinCombos.NUM_WINNING_COMBOS; i++)
{
if (boardData[MathWinCombos.WinningCombos[i, 0]] == EBoardSelection.E_Selection_O &&
boardData[MathWinCombos.WinningCombos[i, 1]] == EBoardSelection.E_Selection_O &&
boardData[MathWinCombos.WinningCombos[i, 2]] == EBoardSelection.E_Selection_O)
{
CopyWinningPositions(ref winningPositions, i);
winner = EBoardSelection.E_Selection_O;
break;
}
else if (boardData[MathWinCombos.WinningCombos[i, 0]] == EBoardSelection.E_Selection_X &&
boardData[MathWinCombos.WinningCombos[i, 1]] == EBoardSelection.E_Selection_X &&
boardData[MathWinCombos.WinningCombos[i, 2]] == EBoardSelection.E_Selection_X)
{
CopyWinningPositions(ref winningPositions, i);
winner = EBoardSelection.E_Selection_X;
break;
}
else
{
//do nothing
}
}
return(winner);
}
public int GetNextBestMove(EBoardSelection [] boardData, EBoardSelection inputMark, bool bIsRandom = false)
{
UnityEngine.Debug.Assert(boardData.Length == MAX_NUM_MARKS, "Number of marks on board cant exceed max");
DebugPrint("GetNextBestMove mark = " + inputMark.ToString());
if (bIsRandom)
{
return(GenRandomMove(boardData));
}
MaxScoreData currPlayerMaxScore = GetMaxScorePositions(boardData, inputMark);
//We have a winner, so return it
if (currPlayerMaxScore.score == WINNING_SCORE)
{
DebugPrint("GetNextBestMove() winning move found ");
return(currPlayerMaxScore.positions [0]);
}
DebugPrint("GetNextBestMove() no winning move found for given player");
//We dont a clear winner, so lets try scoring the opposite player moves.
MaxScoreData oppPlayerMaxScore = GetMaxScorePositions(boardData, GetOppPlayerMark(inputMark));
//Opposite Player has a winner, so block it
if (oppPlayerMaxScore.score == WINNING_SCORE)
{
DebugPrint("GetNextBestMove() block opponent win");
return(oppPlayerMaxScore.positions [0]);
}
DebugPrint("GetNextBestMove() no blocking move found to opponent");
if (oppPlayerMaxScore.score > currPlayerMaxScore.score)
{
DebugPrint("GetNextBestMove() Opposition got a better move");
int randPosition = UnityEngine.Random.Range(0, oppPlayerMaxScore.positions.Count);
return(oppPlayerMaxScore.positions [randPosition]);
}
//Lets find if there is any position which has high score for both players
List <int> match = currPlayerMaxScore.positions.Intersect(oppPlayerMaxScore.positions).ToList <int>();
if (match.Count > 0)
{
//get a random positions from list of match
int randPosition = UnityEngine.Random.Range(0, match.Count);
return(match [randPosition]);
}
else
{
//get a random positions from list of max score positions
int randPosition = UnityEngine.Random.Range(0, currPlayerMaxScore.positions.Count);
return(currPlayerMaxScore.positions [randPosition]);
}
}
private EBoardSelection [] CloneBoardData(EBoardSelection [] boardData)
{
EBoardSelection[] clonedBoard = new EBoardSelection[MAX_NUM_MARKS];
for (int i = 0; i < boardData.Length; i++)
{
clonedBoard [i] = boardData [i];
}
return(clonedBoard);
}
private EBoardSelection GetOppPlayerMark(EBoardSelection mark)
{
UnityEngine.Debug.Assert(mark != EBoardSelection.E_Selection_None, "player needs a valid mark");
if (mark == EBoardSelection.E_Selection_O)
{
return(EBoardSelection.E_Selection_X);
}
return(EBoardSelection.E_Selection_O);
}
private int CalculateScore(EBoardSelection [] boardData, EBoardSelection inputMark, int position)
{
EBoardSelection[] clonedBoard = CloneBoardData(boardData);
clonedBoard [position] = inputMark;
int[] winningPositions = null;
if (EvaluateWin(clonedBoard, ref winningPositions) == inputMark)
{
return(WINNING_SCORE);
}
if (IsGameOver(clonedBoard))
{
return(NO_SCORE);
}
int score = 0;
//How many winning combos are possible with this position
for (int i = 0; i < MathWinCombos.NUM_WINNING_COMBOS; i++)
{
//Check if the given position is part of winning combo
if (MathWinCombos.WinningCombos [i, 0] == position ||
MathWinCombos.WinningCombos [i, 1] == position ||
MathWinCombos.WinningCombos [i, 2] == position)
{
//We can ignore the winning combo, if the oponent already has a mark on it
if (clonedBoard [MathWinCombos.WinningCombos [i, 0]] != GetOppPlayerMark(inputMark) &&
clonedBoard [MathWinCombos.WinningCombos [i, 1]] != GetOppPlayerMark(inputMark) &&
clonedBoard [MathWinCombos.WinningCombos [i, 2]] != GetOppPlayerMark(inputMark))
{
score++;
}
}
}
return(score);
}
