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  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. int minEval(int board[9]);
  6. int maxEval(int board[9]);
  7.  
  8.  
  9. //This function displays the board.
  10. void displayBoard(int board[9]) {
  11. 	for (int i = 0; i<9; i++) {
  12. 		if (board[i] == 0) {
  13. 			cout << i << "\t";
  14. 		}
  15. 		else if (board[i] == 1) {
  16. 			cout << "X\t";
  17. 		}
  18. 		else if (board[i] == -1) {
  19. 			cout << "O\t";
  20. 		}
  21.  
  22. 		if (i == 2 || i == 5 || i == 8) {
  23. 			cout << "\n" << endl;
  24. 		}
  25. 	}
  26. }
  27.  
  28. //This functions checks if the game is won
  29. bool checkWin(int board[9]) {
  30. 	if ((board[0] == board[1] && board[1] == board[2] && board[0] != 0) ||
  31. 		(board[3] == board[4] && board[4] == board[5] && board[4] != 0) ||
  32. 		(board[6] == board[7] && board[7] == board[8] && board[6] != 0)) {
  33. 		return true;
  34. 	}
  35. 	else if ((board[0] == board[3] && board[3] == board[6] && board[0] != 0) ||
  36. 		(board[1] == board[4] && board[4] == board[7] && board[4] != 0) ||
  37. 		(board[2] == board[5] && board[5] == board[8] && board[2] != 0)) {
  38. 		return true;
  39. 	}
  40. 	else if ((board[0] == board[4] && board[4] == board[8] && board[4] != 0) ||
  41. 		(board[2] == board[4] && board[4] == board[6] && board[4] != 0)) {
  42. 		return true;
  43. 	}
  44. 	else {
  45. 		return false;
  46. 	}
  47. }
  48.  
  49. //This function checks for a draw.
  50. bool checkDraw(int board[9]) {
  51. 	int counter = 0;
  52. 	for (int i = 0; i<9; i++) {
  53. 		if (board[i] != 0) {
  54. 			counter++;
  55. 		}
  56. 	}
  57. 	if (counter == 9) {
  58. 		return true;
  59. 	}
  60. 	else {
  61. 		return false;
  62. 	}
  63. }
  64.  
  65. int minEval(int board[9]) {
  66. 	//Checks if the board state is a win and returns 1000, which means max wins.
  67. 	if (checkWin(board)) {
  68. 		return 1000;
  69. 	}
  70. 	//If the game is drawn, it returns 0.
  71. 	else if (checkDraw(board)) {
  72. 		return 0;
  73. 	}
  74. 	//Defines the finalScore, which is the score such that max wins.
  75. 	int finalScore = 1000;
  76. 	//int position;
  77. 	//Loops through the board and if that spot is empty, it places O at the slot and runs maxEval and reverts the board after getting the score.
  78. 	for (int i = 0; i < 9; i++) {
  79. 		if (board[i] == 0) {
  80. 			board[i] = -1;
  81. 			int score = maxEval(board);
  82. 			if (score < finalScore) {
  83. 				finalScore = score;
  84. 				//position = i;
  85. 			}
  86. 			board[i] = 0;
  87. 		}
  88. 	}
  89. 	//cout << position << endl;
  90. 	return finalScore;
  91. }
  92.  
  93. //Does exactly what minEval does with a couple of minor differences.
  94. int maxEval(int board[9]) {
  95. 	if (checkWin(board)) {
  96. 		return -1000;
  97. 	}
  98. 	else if (checkDraw(board)) {
  99. 		return 0;
  100. 	}
  101.  
  102. 	int finalScore = -1000;
  103. 	//int position;
  104. 	for (int i = 0; i < 9; i++) {
  105. 		if (board[i] == 0) {
  106. 			board[i] = 1;
  107. 			int score = minEval(board);
  108. 			if (score > finalScore) {
  109. 				finalScore = score;
  110. 				//position = i;
  111. 			}
  112. 			board[i] = 0;
  113. 		}
  114. 	}
  115. 	//cout << position << endl;
  116. 	return finalScore;
  117. }
  118.  
  119. //This function is supposed to determine which position corresponds to the best score and place either X or 0 on that position.
  120. void playMove(int board[9], int player) {
  121. 	//finalScore is either 1000 or -1000.
  122. 	int finalScore = player * -1000;
  123. 	int position;
  124. 	//Like min and max, it loops through the board and places either an X or an O depending on the input, player, and calls either min or max.
  125. 	for (int i = 0; i < 9; i++) {
  126. 		if (board[i] == 0) {
  127. 			board[i] = player;
  128. 			int score;
  129. 			if (player == 1) {
  130. 				score = maxEval(board);
  131. 			}
  132. 			else {
  133. 				score = minEval(board);
  134. 			}
  135. 			//The added position should correspond to the one with the best score, but on execution, something completely different happens.
  136. 			//The AI makes terrible moves and doesn't play to win.
  137. 			if (player == 1 && score >= finalScore) {
  138. 				finalScore = score;
  139. 				//cout << finalScore << endl;
  140. 				position = i;
  141. 			}
  142. 			else if (player == -1 && score <= finalScore) {
  143. 				finalScore = score;
  144. 				//cout << finalScore << endl;
  145. 				position = i;
  146. 			}
  147. 			board[i] = 0;
  148. 		}
  149. 	}
  150.  
  151. 	board[position] = player;
  152. }
  153.  
  154. int main() {
  155. 	//The starting board with all 0s, indicating the board is empty. 1 is for X and -1 is for O.
  156. 	int matrix[9] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
  157.  
  158. 	//int matrix[9] = { 1, -1, 1, 0, -1, 0, -1, 0, 0 };
  159. 	//int test = maxEval(matrix);
  160. 	//cout << test << endl;
  161. 	//Loops through and plays by itself.
  162. 	for (int i = 0; i < 9; i++) {
  163. 		int player;
  164. 		if (i % 2 == 0) {
  165. 			player = -1;
  166. 		}
  167. 		else {
  168. 			player = 1;
  169. 		}
  170.  
  171. 		playMove(matrix, player);
  172.  
  173. 		displayBoard(matrix);
  174. 		cout << "\n\n";
  175. 	}
  176. 	cin.get();
  177. 	return 0;
  178. }
Success #stdin #stdout 0.04s 3468KB
comments (?)
stdin
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Standard input is empty
stdout
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0	1	2	

3	4	5	

6	7	O	



0	1	2	

3	4	5	

X	7	O	



0	1	2	

3	4	5	

X	O	O	



0	1	2	

3	4	X	

X	O	O	



0	1	2	

3	O	X	

X	O	O	



0	1	2	

X	O	X	

X	O	O	



0	1	O	

X	O	X	

X	O	O	



0	X	O	

X	O	X	

X	O	O	



O	X	O	

X	O	X	

X	O	O
https://ideone.com/6791d4
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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