Tic-tac-toe: Difference between revisions

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ExitApp
</lang>
 
=={{header|C}}==
Opening alternates between human and computer. Computer never loses.
<lang C>#include <stdio.h>
#include <stdlib.h>
 
int b[3][3]; /* board. 0: blank; -1: computer; 1: human */
 
int check_winner()
{
int i;
for (i = 0; i < 3; i++) {
if (b[i][0] && b[i][1] == b[i][0] && b[i][2] == b[i][0])
return b[i][0];
if (b[0][i] && b[1][i] == b[0][i] && b[2][i] == b[0][i])
return b[0][i];
}
if (!b[1][1]) return 0;
 
if (b[1][1] == b[0][0] && b[2][2] == b[0][0]) return b[0][0];
if (b[1][1] == b[2][0] && b[0][2] == b[1][1]) return b[1][1];
 
return 0;
}
 
void showboard()
{
char *t = "X O";
int i, j;
for (i = 0; i < 3; i++, putchar('\n'))
for (j = 0; j < 3; j++)
printf("%c ", t[ b[i][j] + 1 ]);
printf("-----\n");
}
 
#define for_ij for (i = 0; i < 3; i++) for (j = 0; j < 3; j++)
int best_i, best_j;
int test_move(int val, int depth)
{
int i, j, score;
int best = -1, changed = 0;
 
if ((score = check_winner())) return (score == val) ? 1 : -1;
 
for_ij {
if (b[i][j]) continue;
 
changed = b[i][j] = val;
score = -test_move(-val, depth + 1);
b[i][j] = 0;
 
if (score <= best) continue;
if (!depth) {
best_i = i;
best_j = j;
}
best = score;
}
 
return changed ? best : 0;
}
 
char* game(int user)
{
int i, j, k, move, win = 0;
for_ij b[i][j] = 0;
 
printf("Board postions are numbered so:\n1 2 3\n4 5 6\n7 8 9\n");
printf("You have O, I have X.\n\n");
for (k = 0; k < 9; k++, user = !user) {
while(user) {
printf("your move: ");
if (!scanf("%d", &move)) {
scanf("%*s");
continue;
}
if (--move < 0 || move >= 9) continue;
if (b[i = move / 3][j = move % 3]) continue;
 
b[i][j] = 1;
break;
}
if (!user) {
if (!k) { /* randomize if computer opens, less boring */
best_i = rand() % 3;
best_j = rand() % 3;
} else
test_move(-1, 0);
 
b[best_i][best_j] = -1;
printf("My move: %d\n", best_i * 3 + best_j + 1);
}
 
showboard();
if ((win = check_winner()))
return win == 1 ? "You win.\n\n": "I win.\n\n";
}
return "A draw.\n\n";
}
 
int main()
{
int first = 0;
while (1) printf(game(first = !first));
return 0;
}</lang>
 
=={{header|D}}==
Anonymous user