103 lines
2 KiB
C
103 lines
2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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int b[3][3]; /* board. 0: blank; -1: computer; 1: human */
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int check_winner()
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{
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int i;
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for (i = 0; i < 3; i++) {
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if (b[i][0] && b[i][1] == b[i][0] && b[i][2] == b[i][0])
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return b[i][0];
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if (b[0][i] && b[1][i] == b[0][i] && b[2][i] == b[0][i])
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return b[0][i];
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}
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if (!b[1][1]) return 0;
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if (b[1][1] == b[0][0] && b[2][2] == b[0][0]) return b[0][0];
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if (b[1][1] == b[2][0] && b[0][2] == b[1][1]) return b[1][1];
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return 0;
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}
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void showboard()
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{
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const char *t = "X O";
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int i, j;
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for (i = 0; i < 3; i++, putchar('\n'))
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for (j = 0; j < 3; j++)
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printf("%c ", t[ b[i][j] + 1 ]);
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printf("-----\n");
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}
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#define for_ij for (i = 0; i < 3; i++) for (j = 0; j < 3; j++)
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int best_i, best_j;
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int test_move(int val, int depth)
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{
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int i, j, score;
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int best = -1, changed = 0;
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if ((score = check_winner())) return (score == val) ? 1 : -1;
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for_ij {
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if (b[i][j]) continue;
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changed = b[i][j] = val;
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score = -test_move(-val, depth + 1);
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b[i][j] = 0;
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if (score <= best) continue;
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if (!depth) {
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best_i = i;
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best_j = j;
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}
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best = score;
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}
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return changed ? best : 0;
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}
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const char* game(int user)
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{
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int i, j, k, move, win = 0;
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for_ij b[i][j] = 0;
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printf("Board postions are numbered so:\n1 2 3\n4 5 6\n7 8 9\n");
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printf("You have O, I have X.\n\n");
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for (k = 0; k < 9; k++, user = !user) {
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while(user) {
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printf("your move: ");
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if (!scanf("%d", &move)) {
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scanf("%*s");
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continue;
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}
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if (--move < 0 || move >= 9) continue;
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if (b[i = move / 3][j = move % 3]) continue;
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b[i][j] = 1;
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break;
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}
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if (!user) {
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if (!k) { /* randomize if computer opens, less boring */
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best_i = rand() % 3;
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best_j = rand() % 3;
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} else
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test_move(-1, 0);
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b[best_i][best_j] = -1;
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printf("My move: %d\n", best_i * 3 + best_j + 1);
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}
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showboard();
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if ((win = check_winner()))
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return win == 1 ? "You win.\n\n": "I win.\n\n";
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}
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return "A draw.\n\n";
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}
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int main()
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{
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int first = 0;
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while (1) printf("%s", game(first = !first));
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return 0;
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}
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