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  1.     # include "stdio.h"
  2.     # include "limits.h"
  3.  
  4.     int MAX (int x, int y) {
  5.     	if (x > y) {
  6.     		return x;
  7.     	}
  8.     	else {
  9.     		return y;
  10.     	}
  11.     }
  12.  
  13.     int MIN (int x, int y) {
  14.     	if (x < y) {
  15.     		return x;
  16.     	}
  17.     	else {
  18.     		return y;
  19.     	}
  20.     }
  21.  
  22.  
  23.     char gridChar(int i) {
  24.         switch(i) {
  25.             case -1:
  26.                 return 'X';
  27.             case 0:
  28.                 return ' ';
  29.             case 1:
  30.                 return 'O';
  31.         }
  32.     }
  33.  
  34.     void draw(int* b) {
  35.         printf(" %c | %c | %c\n",gridChar(b[0]),gridChar(b[1]),gridChar(b[2]));
  36.         printf("---+---+---\n");
  37.         printf(" %c | %c | %c\n",gridChar(b[3]),gridChar(b[4]),gridChar(b[5]));
  38.         printf("---+---+---\n");
  39.         printf(" %c | %c | %c\n",gridChar(b[6]),gridChar(b[7]),gridChar(b[8]));
  40.     }
  41.  
  42.     int win(const int* board) {
  43.         //determines if a player has won, returns 0 otherwise.
  44.         unsigned wins[8][3] = {{0,1,2},{3,4,5},{6,7,8},{0,3,6},{1,4,7},{2,5,8},{0,4,8},{2,4,6}};
  45.         int i;
  46.         for(i = 0; i < 8; ++i) {
  47.             if(board[wins[i][0]] != 0 &&
  48.                board[wins[i][0]] == board[wins[i][1]] &&
  49.                board[wins[i][0]] == board[wins[i][2]])
  50.                 return board[wins[i][2]];
  51.         }
  52.         return 0;
  53.     }
  54.  
  55.     int alphabeta(int* board, int depth, int alpha, int beta, bool max_player) {
  56.  
  57.     	int score = 0;
  58.     	max_player = true;
  59.  
  60.     	if(depth == 0){
  61.     		return score;
  62.     	}
  63.  
  64.     	if(max_player) {
  65.     		alpha = INT_MIN;
  66.     		while (depth != 0) {
  67.     		score = alphabeta(board, depth - 1, alpha, beta, !max_player);
  68.     			alpha = MAX(alpha, score );
  69.     			if (beta <= alpha) break;
  70.     		}
  71.     		return alpha;
  72.     	}
  73.     	else {
  74.     		beta = INT_MAX;
  75.     		while (depth != 0) {
  76.     			score = alphabeta(board, depth - 1, alpha, beta, !max_player);
  77.     			beta = MIN(beta, score );
  78.     			if (beta <= alpha) break;
  79.     		}
  80.     		return beta;
  81.     	}
  82.     }
  83.  
  84.  
  85.     void computerMove(int* board) {
  86.         int move = -1;
  87.         int score = -2;
  88.         int i;
  89.         for(i = 0; i < 9; ++i) {
  90.             if(board[i] == 0) {
  91.                 board[i] = 1;
  92.                 int tempScore = -alphabeta(board,6, -10000, 10000, true);
  93.                 board[i] = 0;
  94.                 if(tempScore > score) {
  95.                     score = tempScore;
  96.                     move = i;
  97.                 }
  98.             }
  99.         }
  100.         //returns a score based on minimax tree at a given node.
  101.         board[move] = 1;
  102.     }
  103.  
  104.  
  105.     void playerMove(int* board) {
  106.         int move = 0;
  107.         do {
  108.             printf("\nInput move ([0..8]): ");
  109.             scanf("%d", &move);
  110.             printf("\n");
  111.         } while (move >= 9 || move < 0 && board[move] == 0);
  112.         board[move] = -1;
  113.     }
  114.  
  115.     int main() {
  116.         int board[9] = {0,0,0,0,0,0,0,0,0};
  117.         //computer squares are 1, player squares are -1.
  118.         printf("Computer: O, You: X\nPlay (1)st or (2)nd? ");
  119.         int player=0;
  120.         scanf("%d",&player);
  121.         printf("\n");
  122.         unsigned turn;
  123.         for(turn = 0; turn < 9 && win(board) == 0; ++turn) {
  124.             if((turn+player) % 2 == 0)
  125.                 computerMove(board);
  126.             else {
  127.                 draw(board);
  128.                 playerMove(board);
  129.             }
  130.         }
  131.         switch(win(board)) {
  132.             case 0:
  133.                 printf("A draw. How droll.\n");
  134.                 break;
  135.             case 1:
  136.                 draw(board);
  137.                 printf("You lose.\n");
  138.                 break;
  139.             case -1:
  140.                 printf("You win. Inconceivable!\n");
  141.                 break;
  142.         }
  143.     }
  144.  
  145.  
Time limit exceeded #stdin #stdout 5s 3460KB
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https://ideone.com/a30PGn
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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