// Tic Tac Toe Game C++.
// Made By: Aman Singh Bhogal
// Algorithm used for Computer Opponent is Mini Max Algorithm.
#include<iostream> // For Input Output.
#include<conio.h> // For using getch() function.
using namespace std;
class tic_tac_toe
{
// Initializing the Squares:
char square[10] = {'0','1','2','3','4','5','6','7','8','9'};
public:
void display(); // Formatted Output Screen.
int checkwin(); // Constantly Check for winner.
void board(); // Logic for Board.
int make_move(int n,int player); // Used to make Move on Board
void run(); // Handles entire Execution
int minimax_AI(int depth,int isAI); // Mini Max Algorithm for Computer Opponent.
int Find_The_Best_Move(); // Finds best move for AI at any given Instance.
};
int tic_tac_toe::make_move(int n, int player)
{
char mark=(player == 1) ? 'X' : 'O';
int choice =n;
for(int i=1;i<=9;i++)
{
char c = 48 + i;
if(choice == i && square[i] == c)
{
square[i] = mark;
return 0;
}
}
cout<<"Invalid Move! Please try again";
getch();
return -1;
}
void tic_tac_toe::display()
{
// For Windows use: system("cls");
// system("cls");
// For Linux use: system("clear");
system("clear");
cout<<"\t\t\tTic Tac Toe Using Min Max Algorithm."<<endl;
cout<<"\t\t\t Code By: Aman Singh Bhogal"<<endl;
cout << "\t\t\t\t Tic Tac Toe"<<endl;
for(int i=0; i<80; i++)
cout<<"_";
cout<<endl;
}
// Logic to check if any player is winning.
int tic_tac_toe::checkwin()
{
if (square[1] == square[2] && square[2] == square[3])
return ((square[1] == 'X')? 10:-10);
else if (square[4] == square[5] && square[5] == square[6])
return ((square[4] == 'X')? 10:-10);
else if (square[7] == square[8] && square[8] == square[9])
return ((square[7] == 'X')? 10:-10);
else if (square[1] == square[4] && square[4] == square[7])
return ((square[7] == 'X')? 10:-10);
else if (square[2] == square[5] && square[5] == square[8])
return ((square[2] == 'X')? 10:-10);
else if (square[3] == square[6] && square[6] == square[9])
return ((square[3] == 'X')? 10:-10);
else if (square[1] == square[5] && square[5] == square[9])
return ((square[1] == 'X')? 10:-10);
else if (square[3] == square[5] && square[5] == square[7])
return ((square[3] == 'X')? 10:-10);
else if (square[1] != '1' && square[2] != '2' && square[3] != '3' && square[4] != '4' && square[5] != '5' && square[6] != '6' && square[7] != '7' && square[8] != '8' && square[9] != '9')
return 2;
return 0;
}
// Board of the Game
void tic_tac_toe::board()
{
display();
cout<<endl << "\t\t\t AI (X) - Player 2 (O)" << endl << endl;
cout << "\t\t\t _________________" << endl;
cout << "\t\t\t | | | |" << endl;
cout << "\t\t\t | " << square[1] << " | " << square[2] << " | " << square[3] <<" |"<< endl;
cout << "\t\t\t |_____|_____|_____|" << endl;
cout << "\t\t\t | | | |" << endl;
cout << "\t\t\t | " << square[4] << " | " << square[5] << " | " << square[6] <<" |"<< endl;
cout << "\t\t\t |_____|_____|_____|" << endl;
cout << "\t\t\t | | | |" << endl;
cout << "\t\t\t | " << square[7] << " | " << square[8] << " | " << square[9] <<" |" << endl;
cout << "\t\t\t |_____|_____|_____|" << endl << endl;
cout<<endl<<"To Exit Enter Q/q."<<endl;
}
// minimax_AI() is a recursive function that tries to find the best possible move for the Computer player.
int tic_tac_toe::minimax_AI(int depth,int isAI)
{
int cost = checkwin();
if(cost == 10 || cost == -10)
return cost;
if(cost == 2)
return 0;
if(isAI)
{
int best = -1000;
for(int i=0; i<3; i++)
{
for(int j=0; j<3; j++)
{
int p = i*3 + j +1;
char c = 48 + p;
if(square[p] == c)
{
square[p] = 'X';
best = max(best, minimax_AI(depth + 1, 0));
square[p] = c;
}
}
}
return best;
}
else
{
int best = 1000;
for(int i=0; i<3; i++)
{
for(int j=0; j<3; j++)
{
int p = i*3 + j +1;
char c = 48 + p;
if(square[p] == c)
{
square[p] = 'O';
best = min(best, minimax_AI(depth + 1, 1));
square[p] = c;
}
}
}
return best;
}
}
// Finc_The_Best_Move() makes use of the minimax_AI() function to make the move for computer player.
int tic_tac_toe::Find_The_Best_Move()
{
int bestscore = -1000;
int bestmove = -1;
for(int i=0; i< 3; i++)
{
for(int j=0; j<3; j++)
{
int p = (i*3) + j +1;
char c = 48 + p;
if(square[p] == c)
{
square[p] = 'X';
int moveScore = minimax_AI(0,0);
square[p] = c;
if(moveScore > bestscore)
{
bestmove = p;
bestscore = moveScore;
}
}
}
}
return bestmove;
}
// run() function handles the entire execution of the program.
void tic_tac_toe::run()
{
board();
int player=1,win=0;
string n;
while(!win)
{
player = (player%2)? 1:2;
if(player == 2)
{
int k;
cout<<endl<<"Human's Turn, Enter your Choice: ";
cin>>n;
if(n == "Q" || n == "q")
exit(0);
else
k = stoi(n);
int i = make_move(k,player);
if(i==-1)
continue;
player++;
}
else
{
int move = Find_The_Best_Move();
make_move(move,player);
board();
cout<<"\t\t\t\tAI's Move."<<endl<<endl;
cout<<"Please Press any key to continue.......";
getch();
player++;
}
board();
win = checkwin();
}
if(win==10 || win==-10)
cout<<"\t\t\t\tPlayer "<<((--player==1)?"AI":"Human")<<" Wins!"<<endl<<endl;
else
cout<<"\t\t\t\t Game Draw!"<<endl<<endl;
}
// This is the main function of the Program.
int main()
{
tic_tac_toe t;
t.run();
return 0;
}
