minix/commands/simple/ttt.c

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2005-04-21 16:53:53 +02:00
/* tic tac toe (noughts and crosses) Author: Warren Toomey */
/* Copyright 1988 by Warren Toomey wkt@cs.adfa.oz.au[@uunet.uu.net]
*
* You may freely copy or distribute this code as long as this notice
* remains intact.
*
* You may modify this code, as long as this notice remains intact, and
* you add another notice indicating that the code has been modified.
*
* You may NOT sell this code or in any way profit from this code without
* prior agreement from the author.
*/
/* Compile with cc -o tic tic.c -lcurses -ltermcap */
#include <stdlib.h>
#include <time.h>
#ifdef CURSES
#include <curses.h>
#endif
#include <stdio.h>
#ifndef CURSES
#define printw printf
#endif
typedef struct {
int value; /* The move returned by the */
int path; /* alphabeta consists of a value */
} MOVE; /* and an actual move (path) */
_PROTOTYPE(int main, (void));
_PROTOTYPE(int stateval, (int board [], int whosemove));
_PROTOTYPE(MOVE alphabeta, (int board [], int whosemove, int alpha, int beta));
_PROTOTYPE(void draw, (int board []));
_PROTOTYPE(void getmove, (int board []));
_PROTOTYPE(int endofgame, (int board []));
_PROTOTYPE(int randommove, (void));
/* Static evaluator. Returns 100 if we have 3 in a row -100 if they have 3
* in a row
*
* Board is array of 9 ints, where 0=empty square 1=our move 4= their move
*
* and board is indices 0 1 2 3 4 5 6 7 8 */
int stateval(board, whosemove)
int board[];
int whosemove;
{
static int row[8][3] = {{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, /* Indices of 3in-a-rows */
{0, 3, 6}, {1, 4, 7}, {2, 5, 8},
{0, 4, 8}, {2, 4, 6}};
int temp; /* Temp row results */
int i, j; /* Loop counters */
int side; /* Depth multiplier */
int win, lose;
if (whosemove == 1) {
win = 100;
lose = -100;
side = 1;
} else {
/* Multiply by -1 if */
win = -100;
lose = 100;
side = -1;
} /* not out move */
for (i = 0; i < 8; i++) { /* For every 3-in-a-row */
temp = 0;
for (j = 0; j < 3; j++) /* Add up the board values */
temp += board[row[i][j]];
if (temp == 3) return(win); /* We've got 3 in a row */
if (temp == 12) return (lose); /* They've got 3 in a row */
}
return(0); /* Finally return sum */
}
MOVE alphabeta(board, whosemove, alpha, beta) /* Alphabeta: takes a board, */
int board[]; /* whose move, alpha & beta cutoffs, */
int whosemove; /* and returns a move to make and */
int alpha; /* the value that the move has */
int beta;
{
MOVE result, successor;
int best_score, i, best_path, mademove;
result.value = stateval(board, whosemove); /* Work out the board's */
/* Static value */
if ((result.value == 100) || /* If a win or loss already */
(result.value == -100))
return(result); /* return the result */
best_score = beta; /* Ok, set worst score */
mademove = 0; /* to the beta cutoff */
for (i = 0; i < 9; i++) {
if (board[i] == 0) { /* For all valid moves */
mademove = 1;
board[i] = whosemove; /* make the move on board */
successor = alphabeta(board, 5 - whosemove, -best_score - 1, -alpha - 1);
/* Get value of the move */
board[i] = 0; /* Take move back */
if (-successor.value > best_score) { /* If a better score */
best_score = -successor.value; /* update our score */
best_path = i; /* and move */
if (best_score > alpha)
break; /* If we've beaten alpha */
} /* return immediately */
}
}
if (mademove) {
result.value = best_score; /* Finally return best score */
result.path = best_path;/* and best move */
}
return(result); /* If no move, return static result */
}
void draw(board) /* Draw the board */
int board[];
{
int i, j, row;
static char out[] = " X O"; /* Lookup table for character */
row = 6;
#ifdef CURSES
move(row, 0);
#endif
for (j = 0; j < 9; j += 3) {
printw(" %d | %d | %d ", j, j + 1, j + 2);
for (i = 0; i < 3; i++) {
printw("%c ", out[board[j + i]]);
if (i < 2) printw("| ");
}
if (j < 4) {
#ifdef CURSES
move(++row, 0);
#else
printw("\n");
#endif
printw("---+---+--- ---+---+---");
}
#ifdef CURSES
move(++row, 0);
#else
printw("\n");
#endif
}
#ifdef CURSES
refresh();
#else
printw("\n");
#endif
}
void getmove(board) /* Get a player's move */
int board[];
{
int Move;
int ItemsRead;
char dumc;
do {
do {
#ifdef CURSES
move(9, 40);
printw("Your move: "); /* Prompt for move */
refresh();
#else
printw("Your move: "); /* Prompt for move */
#endif
ItemsRead = scanf("%d", &Move); /* Input the move */
if (ItemsRead == 0) scanf("%c", &dumc); /* Remove the offending character */
}
while (ItemsRead != 1);
}
while (board[Move]);
board[Move] = 4; /* If legal, add to board */
draw(board); /* Draw the board */
}
int endofgame(board) /* Determine end of the game */
int board[];
{
int eval;
int count;
eval = stateval(board, 1);
#ifdef CURSES
move(20, 25);
#endif
if (eval == 100) {
printw("I have beaten you.\n");
return(1);
}
if (eval == -100) {
printw("Bus error (core dumped)\n");
return(1);
}
count = 0;
for (eval = 0; eval < 9; eval++)
if (board[eval] != 0) count++;
if (count == 9) {
printw("A draw!\n");
return(1);
}
#ifdef CURSES
refresh();
#endif
return(0);
}
int randommove()
{ /* Make an initial random move */
int i;
i = abs((int) time((long *) 0));
return(i % 9);
}
int main()
{ /* The actual game */
int i, board[9];
char ch;
MOVE ourmove;
for (i = 0; i < 9; i++) board[i] = 0; /* Initialise the board */
#ifdef CURSES
initscr();
clear();
refresh();
#endif
printw(" TIC TAC TOE \n\n");
printw(" Your moves are 'O'\n");
printw(" My moves are 'X'\n\n");
#ifdef CURSES
move(5, 0);
printw("Do you wish to move first: ");
refresh();
while (scanf("%c", &ch) != 1);
move(5, 0);
printw(" ......."); /* Kludge to get rid */
refresh();
move(5, 0);
printw(" "); /* of input letter */
refresh();
#else
do
printw("Do you wish to move first: ");
while (scanf("%c", &ch) != 1);
#endif
if ((ch != 'y') && (ch != 'Y')) {
i = randommove(); /* If we move first */
board[i] = 1; /* make it random */
#ifdef CURSES
move(7, 42);
printw("My move: %d\n", i);
refresh();
#else
printw("My move: %d\n", i);
#endif
}
draw(board);
getmove(board);
while (1) {
ourmove = alphabeta(board, 1, 99, -99); /* Get a move for us;
* return wins */
/* Immediately & ignore losses */
board[ourmove.path] = 1;/* and make it */
#ifdef CURSES
move(7, 42);
printw("My move: %d\n", ourmove.path);
refresh();
#else
printw("My move: %d\n", ourmove.path);
#endif
draw(board);
if (endofgame(board)) break; /* If end of game, exit */
getmove(board); /* Get opponent's move */
if (endofgame(board)) break; /* If end of game, exit */
}
#ifdef CURSES
endwin();
#endif
return(0);
}