tictactoe

commit 586c25883c6322d0fd0e0fd47305f074dadc6837
parent 106ccb207c60f0b4f26af0aa3772e44a96750ea2
Author: Wilson Gheen <wilson@wilsonrgheen.com>
Date:   Sun, 18 Dec 2022 08:38:08 -0600

WIP -- refactor to prevent repeating code in blocking/non-blocking "AIs"

Diffstat:
M
tictactoe.c
 | 
2
+-
M
tictactoe.h
 | 
62
++++++++++++++++++++++++++++----------------------------------

2 files changed, 29 insertions(+), 35 deletions(-)
diff --git a/tictactoe.c b/tictactoe.c
@@ -33,7 +33,7 @@ char play(char (*get_move)(char*, char), char (*get_move_2)(char*, char)) {
         print_board(board);
     for(int turns=0; !winner && turns < 9; turns++) {
         winner = (turns & 1) ? get_move(board, player) : get_move_2(board, player);
-        player = (player == 'O' ? 'X' : 'O');
+        player = OPPONENT;
         if(SIDE_BY_SIDE)
             print_board_offset(board, turns * 10, 0, 0);
         else
diff --git a/tictactoe.h b/tictactoe.h
@@ -3,6 +3,8 @@
 #include <string.h>
 #include <time.h>
 
+/*#define NO_PRINT_BOARD*/
+
 #define SCRATCH_BOARD "XXOOOXXOX"
 #define X_WINS_COLUMN "XXOXOOXOX"
 #define X_WINS_DIAG   "XOO XOOXX"
@@ -12,7 +14,8 @@
 #define O_WINS_ROW    " XXXOXOOO"
 
 #define scase(s1, s2)    if (!strcmp(s1, s2))
-/*#define NO_PRINT_BOARD*/
+
+#define OPPONENT    (player == 'O' ? 'X' : 'O')
 
 /*typedef void (*board_fn)(char *, char);*/
 static char  the_desired_board[32];
@@ -137,43 +140,34 @@ char get_random_move(char *board, char player) {
     board[legal_moves[get_rand(lm_ind)]] = player;
     return get_winner_or_winning_moves(board, NULL);
 }
-static char try_get_winning_move(char *board, char player) {
-    char winning_moves[9] = "";
-    int my_winning_moves[5];
-    int mwm_ind = 0;
-    get_winner_or_winning_moves(board, winning_moves);
-    for(int i=0; i < 9; i++)
-        if((winning_moves[i] & player) == player)
-            my_winning_moves[mwm_ind++] = i;
-    if(mwm_ind) {
-        board[my_winning_moves[get_rand(mwm_ind)]] = player;
+static char try_make_winning_move(char *board, char player, _Bool block_opponent) {
+    char all_winning_moves[9] = "";
+    get_winner_or_winning_moves(board, all_winning_moves);
+    int my_winning_moves_inds[5], his_winning_moves_inds[5];
+    int mwm_ind_ind = 0, hwm_ind_ind = 0;
+    for(int i=0; i < 9; i++) {
+        /* Get all possible winning moves, including optionally the opponent's;
+         * add indices of each to an array ... */
+        if((all_winning_moves[i] & player) == player)
+            my_winning_moves_inds[mwm_ind_ind++] = i;
+        else if(block_opponent && all_winning_moves[i] == OPPONENT)
+            his_winning_moves_inds[hwm_ind_ind++] = i;
+    }
+    /* ...then choose one at random, mine if possible, else the opponent's (if opted for) */
+    if(mwm_ind_ind) {
+        board[my_winning_moves_inds[get_rand(mwm_ind_ind)]] = player;
         return player;
     }
-    return 0;
+    if(hwm_ind_ind) {
+        board[his_winning_moves_inds[get_rand(hwm_ind_ind)]] = player;
+        /* N.B. This will not be reached if the move is a winning move for both players */
+        return 0;
+    }
+    return get_random_move(board, player);
 }
 char get_winning_move_else_random(char *board, char player) {
-    char winner = try_get_winning_move(board, player);
-    if(winner)
-        return winner;
-    else
-        return get_random_move(board, player);
+    return try_make_winning_move(board, player, 0);
 }
 char get_winning_move_else_block_else_random(char *board, char player) {
-    char winner = try_get_winning_move(board, player);
-    if(winner) return winner;
-    char winning_moves[9] = "";
-    int his_winning_moves[5];
-    int hwm_ind = 0;
-    char opponent = (player == 'O' ? 'X' : 'O');
-    get_winner_or_winning_moves(board, winning_moves);
-    for(int i=0; i < 9; i++)
-        if(winning_moves[i] == opponent)
-            his_winning_moves[hwm_ind++] = i;
-    if(hwm_ind) {
-        board[his_winning_moves[get_rand(hwm_ind)]] = player;
-        /*N.B. This will not be reached if the move is a winning move for both players */
-        return 0;
-    }
-    else
-        return get_random_move(board, player);
+    return try_make_winning_move(board, player, 1);
 }