// functions
void instructions()
{
cout << "Welcome to the ultimate man-machine showdown: Tic-Tac-Toe.\n";
cout << "--where human brain is pit against silicon processor\n\n";
cout << "Make your move known by entering a number, 0 - 8. The number\n";
cout << "corresponds to the desired board position, as illustrated:\n\n";
int askNumber(string question, int high, int low)
{
int number;
do
{
cout << question << " (" << low << " - " << high << "): ";
cin >> number;
} while (number > high || number < low);
return number;
}
char humanPiece()
{
char go_first = askYesNo("Do you require the first move?");
if (go_first == 'y')
{
cout << "\nThen take the first move. You will need it.\n";
char go_first = askYesNo("Do you require the first move?");
if (go_first == 'y')
{
cout << "\nThen take the first move. You will need it.\n";
return X;
}
else
{
cout << "\nYour bravery will be your undoing... I will go first.\n";
return O;
}
}
else
{
cout << "\nYour bravery will be your undoing... I will go first.\n";
return O;
}
}
// if any winning row has three values that are the same (and not EMPTY),
// then we have a winner
for(int row = 0; row < TOTAL_ROWS; ++row)
{
if ( (board[WINNING_ROWS[row][0]] != EMPTY) &&
(board[WINNING_ROWS[row][0]] == board[WINNING_ROWS[row][1]]) &&
(board[WINNING_ROWS[row][1]] == board[WINNING_ROWS[row][2]]) )
{
return board[WINNING_ROWS[row][0]];
}
}
// since nobody has won, check for a tie (no empty squares left)
if (count(board.begin(), board.end(), EMPTY) == 0)
return TIE;
// since nobody has won and it isn't a tie, the game ain't over
return NO_ONE;
}
int humanMove(const vector<char>& board, char human)
{
int move = askNumber("Where will you move?", (board.size() - 1));
while (!isLegal(move, board))
{
cout << "\nThat square is already occupied, foolish human.\n";
move = askNumber("Where will you move?", (board.size() - 1));
}
cout << "Fine...\n";
return move;
}
int computerMove(vector<char> board, char computer)
{
unsigned int move = 0;
bool found = false;
//if computer can win on next move, that’s the move to make
while (!found && move < board.size())
{
if (isLegal(move, board))
{
//try move
board[move] = computer;
//test for winner
found = winner(board) == computer;
//undo move
board[move] = EMPTY;
}
if (!found)
{
++move;
}
}
//otherwise, if opponent can win on next move, that's the move to make
if (!found)
{
move = 0;
char human = opponent(computer);
while (!found && move < board.size())
{
if (isLegal(move, board))
{
//try move
board[move] = human;
//test for winner
found = winner(board) == human;
//undo move
board[move] = EMPTY;
}
if (!found)
{
++move;
}
}
}
//otherwise, moving to the best open square is the move to make
if (!found)
{
move = 0;
unsigned int i = 0;
const int BEST_MOVES[] = {4, 0, 2, 6, 8, 1, 3, 5, 7};
//pick best open square
while (!found && i < board.size())
{
move = BEST_MOVES[i];
if (isLegal(move, board))
{
found = true;
}
++i;
}
}
cout << "I shall take square number " << move << endl;
return move;
}
void announceWinner(char winner, char computer, char human)
{
if (winner == computer)
{
cout << winner << "'s won!\n";
cout << "As I predicted, human, I am triumphant once more -- proof\n";
cout << "that computers are superior to humans in all regards.\n";
}
else if (winner == human)
{
cout << winner << "'s won!\n";
cout << "No, no! It cannot be! Somehow you tricked me, human.\n";
cout << "But never again! I, the computer, so swear it!\n";
}
else
{
cout << "It's a tie.\n";
cout << "You were most lucky, human, and somehow managed to tie me.\n";
cout << "Celebrate... for this is the best you will ever achieve.\n";
}
}