// looks through all cellLines to see if any are completely filled, and returns the line if so, null otherwise
public static CellButton[] GetWinningLine()
{
foreach (var line in cellLines)
{
LineStatus lineStatus = GetLineStatus(line);
if (lineStatus.CellsTaken == TileTacToe.BOARD_SIZE)
{
return(line); // all cells in the line were taken, this must be the winning one
}
}
return(null); // no winning line was found
}
// this function takes a line and returns a LineStatus (IsWinnable, Owner, CellsTaken) to describe its state
private static LineStatus GetLineStatus(CellButton[] line)
{
LineStatus status = new LineStatus();
for (int i = 0; i < line.Length; i++)
{
if (status.Owner == 0 && line[i].Owner > 0) // if this is the first unowned cell,
{
status.Owner = line[i].Owner; // save owner in status
status.CellsTaken++; // and increment count of cells taken
}
else if (status.Owner > 0 && line[i].Owner != 0) // if line already has an owned cell and this cell is also owned
{
if (line[i].Owner != status.Owner) // if this cell's owner is different than line's existing owner,
{
status.IsWinnable = false; // then this line is unwinnable
return(status); // don't care about the rest, return status immediately
}
status.CellsTaken++; // add one to cells taken
}
}
return(status);
}
// this returns a numerical weight or value for a line of cells, to choose which line for the computer to play
// it assumes TileTacToe.CurrentTurn is the current player and any other players are opponents
private static int GetLineWeight(CellButton[] line)
{
int majorWeight = 0; // this is how important it is to place a cell on the line
int minorWeight = 0; // adjusted by how important the line is strategically (the total weight of cells in the line)
LineStatus status = GetLineStatus(line);
bool isOpponents = (status.Owner != TileTacToe.CurrentTurn); // true if the line is occupied by an opponent
if (status.IsWinnable) // only care about lines that can win; unwinnable lines can remain 0 weight
{
if (TileTacToe.Difficulty == 0) // easy difficulty
{
// in easy mode, line weights are a bit less intelligent
if (status.CellsTaken == 3 && !isOpponents) // if computer has three cells in a line, highest priority to win
{
majorWeight = 6;
}
else if (status.CellsTaken > 1) // otherwise randomly pick any line with more than one owned cell
{
majorWeight = 4;
}
else if (status.CellsTaken == 1) // otherwise pick any line with just one owned cell
{
majorWeight = 2;
}
else // empty lines take lowest priority in easy mode
{
majorWeight = 1;
}
}
else // hard difficulty
{
// easy difficulty exists because I've not won a game with the following weights!
if (status.CellsTaken == 3 && !isOpponents) // if computer has three cells in a line, highest priority to win
{
majorWeight = 6;
}
else if (status.CellsTaken == 3) // if opponent has three cells in a line, block it
{
majorWeight = 5;
}
else if (status.CellsTaken == 2) // if either player has two cells in a line, equal weight
{
majorWeight = 4;
}
else if (status.CellsTaken == 1 && !isOpponents) // if computer has one cell in a line, claim it before following
{
majorWeight = 3;
}
else if (status.CellsTaken == 0) // if the line is empty
{
majorWeight = 2;
}
else // lastly, if the opponent has one cell in a line, can ignore it for now
{
majorWeight = 1;
}
}
majorWeight *= 100; // multiply major weight by 100, minor weight will take up lower two digits
// add up minorWeight which is the sum of the cell's weights to break ties when two lines have equal weight
foreach (var cell in line)
{
minorWeight += cell.Weight;
}
}
// a total weight is majorWeight + minorWeight
return(majorWeight + minorWeight);
}