#include <iostream>

using namespace std;

int turn = 0, place;
bool Xwin = false, Owin = false, invalid_input = false;
char pos1 = ' ', pos2 = ' ', pos3 = ' ',
     pos4 = ' ', pos5 = ' ', pos6 = ' ',
     pos7 = ' ', pos8 = ' ', pos9 = ' ';
// This problem can be made way easier using an array, see other solution.
char input_char;

/*
 * +2 for successful print out of the game grid
 * +2 for successful input system
 * +2 for successful game over via filled grid
 * +2 for successful game over via either side winning
 * +2 for checking whether if inputs are valid
 */

int main()
{
	while(!Xwin && !Owin && turn < 9)	// Game Over check loop
	{
		// Print out the game grid
		cout << "+---+---+---+" << endl
		     << "| " << pos1 << " | " << pos2 << " | " << pos3 << " |\n"
		     << "+---+---+---+" << endl
                     << "| " << pos4 << " | " << pos5 << " | " << pos6 << " |\n"
		     << "+---+---+---+" << endl
                     << "| " << pos7 << " | " << pos8 << " | " << pos9 << " |\n"
		     << "+---+---+---+" << endl;

		if(turn % 2 == 0)	// Even number turns are X turns
			input_char = 'X';
		else			// Odd number turns are O turns
			input_char = 'O';

		do	// This loop is for input validation
		{
			cout << "Place " << input_char << " at: "; 
			cin >> place;
			cin.ignore();

			if(place < 1 || place > 9)	// Allows only 1-9 as inputs
			{
				invalid_input = true;
				cout << "Invalid input! 1-9 only.\n";
			}
			else	// Check that the position entered isn't already used
			{
				switch(place)
				{
					case 1:
						invalid_input = (pos1 != ' ');
						break;
					case 2:
						invalid_input = (pos2 != ' ');
						break;
					case 3:
						invalid_input = (pos3 != ' ');
						break;
					case 4:
						invalid_input = (pos4 != ' ');
						break;
					case 5:
						invalid_input = (pos5 != ' ');
						break;
					case 6:
						invalid_input = (pos6 != ' ');
						break;
					case 7:
						invalid_input = (pos7 != ' ');
						break;
					case 8:
						invalid_input = (pos8 != ' ');
						break;
					case 9:
						invalid_input = (pos9 != ' ');
						break;
				}
				if(invalid_input)
					cout << "Invalid input! Position already filled.\n";
			}
		} while(invalid_input);

		switch(place)	// Proceed with putting the marker in place
		{
			case 1:
				pos1 = input_char;
				break;
			case 2:
                                pos2 = input_char;
                                break;
			case 3:
                                pos3 = input_char;
                                break;
			case 4:
                                pos4 = input_char;
                                break;
			case 5:
                                pos5 = input_char;
                                break;
			case 6:
                                pos6 = input_char;
                                break;
			case 7:
                                pos7 = input_char;
                                break;
			case 8:
                                pos8 = input_char;
                                break;
			case 9:
                                pos9 = input_char;
                                break;
		}

		// Check whether if there's 3 in a row (Manually check all 8 possible win scenarios)
		if(turn >= 4) // Perform the check only after the 5th turn, the minimum to get 3 of a kind
		{
			if(pos1 == pos2 && pos2 == pos3)	// Top row victory
			{
				if(pos1 == 'X')
					Xwin = true;
				else if(pos1 == 'O')	// Don't use else because we want to exclude spaces
					Owin = true;
			}
			else if(pos4 == pos5 && pos5 == pos6)	// Middle row victory
			{
				if(pos4 == 'X')
					Xwin = true;
				else if(pos4 == 'O')
					Owin = true;
			}
			else if(pos7 == pos8 && pos8 == pos9)	// Bottom row victory
			{
				if(pos7 == 'X')
					Xwin = true;
				else if(pos7 == 'O')
					Owin = true;
			}
			else if(pos1 == pos4 && pos4 == pos7)	// Left column victory
			{
				if(pos4 == 'X')
					Xwin = true;
				else if(pos4 == 'O')
					Owin = true;
			}
			else if(pos2 == pos5 && pos5 == pos8)	// Middle column victory
			{
				if(pos5 == 'X')
					Xwin = true;
				else if(pos5 == 'O')
					Owin = true;
			}
			else if(pos3 == pos6 && pos6 == pos9)	// Right column victory
			{
				if(pos6 == 'X')
					Xwin = true;
				else if(pos6 == 'O')
					Owin = true;
			}
			else if(pos1 == pos5 && pos5 == pos9)	// Back diagonal victory
			{
				if(pos1 == 'X')
					Xwin = true;
				else if(pos1 == 'O')
					Owin = true;
			}
			else if(pos3 == pos5 && pos5 == pos7)	// Forward diagonal victory
			{
				if(pos3 == 'X')
					Xwin = true;
				else if(pos3 == 'O')
					Owin = true;
			}
		}
		
		turn++;		
	}

	// Display the final results
	cout << "+---+---+---+" << endl
             << "| " << pos1 << " | " << pos2 << " | " << pos3 << " |\n"
             << "+---+---+---+" << endl
             << "| " << pos4 << " | " << pos5 << " | " << pos6 << " |\n"
             << "+---+---+---+" << endl
             << "| " << pos7 << " | " << pos8 << " | " << pos9 << " |\n"
             << "+---+---+---+" << endl;

	cout << "Game Over - ";
	if(Xwin)
		cout << "X wins!" << endl;
	else if(Owin)
		cout << "O wins!" << endl;
	else
		cout << "Draw" << endl;

	return 0;
}