ticTACtoe.cpp

// A C++ Program to play tic-tac-toe  
#include <bits/stdc++.h>  
using namespace std;  
#define COMPUTER 1  
#define HUMAN 2  
#define SIDE 3 // Length of the board  
// Computer will move with 'O'  
// and human with 'X'  
#define COMPUTERMOVE 'O'  
#define HUMANMOVE 'X'  
// A function to show the current board status  
void showBoard(char board[][SIDE])  
{  
    printf("\n\n");  
  
    printf("\t\t\t %c | %c | %c \n", board[0][0],  
           board[0][1], board[0][2]);  
    printf("\t\t\t--------------\n");  
    printf("\t\t\t %c | %c | %c \n", board[1][0],  
           board[1][1], board[1][2]);  
    printf("\t\t\t--------------\n");  
    printf("\t\t\t %c | %c | %c \n\n", board[2][0],  
           board[2][1], board[2][2]);  
  
    return;  
}  
  
// A function to show the instructions  
void showInstructions()  
{  
    printf("\t\t\t Tic-Tac-Toe\n\n");  
    printf("Choose a cell numbered from 1 to 9 as below"  
           " and play\n\n");  
  
    printf("\t\t\t 1 | 2 | 3 \n");  
    printf("\t\t\t--------------\n");  
    printf("\t\t\t 4 | 5 | 6 \n");  
    printf("\t\t\t--------------\n");  
    printf("\t\t\t 7 | 8 | 9 \n\n");  
  
    printf("-\t-\t-\t-\t-\t-\t-\t-\t-\t-\n\n");  
  
    return;  
}  
  
// A function to initialise the game  
void initialise(char board[][SIDE], int moves[])  
{  
    // Initiate the random number generator so that  
    // the same configuration doesn't arises  
    srand(time(NULL));  
  
    // Initially the board is empty  
    for (int i = 0; i < SIDE; i++)  
    {  
        for (int j = 0; j < SIDE; j++)  
            board[i][j] = ' ';  
    }  
  
    // Fill the moves with numbers  
    for (int i = 0; i < SIDE * SIDE; i++)  
        moves[i] = i;  
  
    // randomise the moves  
    random_shuffle(moves, moves + SIDE * SIDE);  
  
    return;  
}  
  
// A function to declare the winner of the game  
void declareWinner(int whoseTurn)  
{  
    if (whoseTurn == COMPUTER)  
        printf("COMPUTER has won\n");  
    else  
        printf("HUMAN has won\n");  
    return;  
}  
  
// A function that returns true if any of the row  
// is crossed with the same player's move  
bool rowCrossed(char board[][SIDE])  
{  
    for (int i = 0; i < SIDE; i++)  
    {  
        if (board[i][0] == board[i][1] &&  
            board[i][1] == board[i][2] &&  
            board[i][0] != ' ')  
            return (true);  
    }  
    return (false);  
}  
  
// A function that returns true if any of the column  
// is crossed with the same player's move  
bool columnCrossed(char board[][SIDE])  
{  
    for (int i = 0; i < SIDE; i++)  
    {  
        if (board[0][i] == board[1][i] &&  
            board[1][i] == board[2][i] &&  
            board[0][i] != ' ')  
            return (true);  
    }  
    return (false);  
}  
  
// A function that returns true if any of the diagonal  
// is crossed with the same player's move  
bool diagonalCrossed(char board[][SIDE])  
{  
    if (board[0][0] == board[1][1] &&  
        board[1][1] == board[2][2] &&  
        board[0][0] != ' ')  
        return (true);  
  
    if (board[0][2] == board[1][1] &&  
        board[1][1] == board[2][0] &&  
        board[0][2] != ' ')  
        return (true);  
  
    return (false);  
}  
  
// A function that returns true if the game is over  
// else it returns a false  
bool gameOver(char board[][SIDE])  
{  
    return (rowCrossed(board) || columnCrossed(board) || diagonalCrossed(board));  
}  
  
// A function to play Tic-Tac-Toe  
void playTicTacToe(int whoseTurn)  
{  
    // A 3*3 Tic-Tac-Toe board for playing  
    char board[SIDE][SIDE];  
  
    int moves[SIDE * SIDE];  
  
    // Initialise the game  
    initialise(board, moves);  
  
    // Show the instructions before playing  
    showInstructions();  
  
    int moveIndex = 0, x, y;  
  
    // Keep playing till the game is over or it is a draw  
    while (gameOver(board) == false &&  
           moveIndex != SIDE * SIDE)  
    {  
        if (whoseTurn == COMPUTER)  
        {  
            x = moves[moveIndex] / SIDE;  
            y = moves[moveIndex] % SIDE;  
            board[x][y] = COMPUTERMOVE;  
            printf("COMPUTER has put a %c in cell %d\n",  
                   COMPUTERMOVE, moves[moveIndex] + 1);  
            showBoard(board);  
            moveIndex++;  
            whoseTurn = HUMAN;  
        }  
  
        else if (whoseTurn == HUMAN)  
        {  
            x = moves[moveIndex] / SIDE;  
            y = moves[moveIndex] % SIDE;  
            board[x][y] = HUMANMOVE;  
            printf("HUMAN has put a %c in cell %d\n",  
                   HUMANMOVE, moves[moveIndex] + 1);  
            showBoard(board);  
            moveIndex++;  
            whoseTurn = COMPUTER;  
        }  
    }  
  
    // If the game has drawn  
    if (gameOver(board) == false &&  
        moveIndex == SIDE * SIDE)  
        printf("It's a draw\n");  
    else  
    {  
        // Toggling the user to declare the actual  
        // winner  
        if (whoseTurn == COMPUTER)  
            whoseTurn = HUMAN;  
        else if (whoseTurn == HUMAN)  
            whoseTurn = COMPUTER;  
  
        // Declare the winner  
        declareWinner(whoseTurn);  
    }  
    return;  
}  
  
// Driver program  
int main()  
{  
    // Let us play the game with COMPUTER starting first  
    playTicTacToe(COMPUTER);  
  
    return (0);  
}