depth limit rollouts

uttt.c

@@ -916,14 +916,15 @@ struct ut_move ut_minimax(int (*value)(const struct ut_state *state), const stru
 	return best_move;
 }
 
-#define UT_RDEPTH 1
+#define UT_RDEPTH 2
+#define UT_RTURNS 2
 int ut_rollout(const struct ut_state *state)
 {
 
 	struct ut_state rstate = *state;
 	int moves = 0;
 	char winner;
-	while((winner = ut_winner(&rstate)) == '\0')
+	while((winner = ut_winner(&rstate)) == '\0' && moves < UT_RTURNS)
 	{
 		if(ut_move(&rstate, &rstate,
 			   ut_minimax(ut_value, &rstate, UT_RDEPTH)))
@@ -932,7 +933,9 @@ int ut_rollout(const struct ut_state *state)
 		}
 		moves++;
 	}
-	return (winner == 'X') ? (UT_VALUEMAX - moves) : (winner == 'O') ? (UT_VALUEMIN + moves) : 0;
+	return  (winner == 'X') ? (UT_VALUEMAX - moves) :
+		(winner == 'O') ? (UT_VALUEMIN + moves) :
+		(winner == ' ') ? 0 : ut_value(&rstate);
 }
 
 #define UT_DEPTH 5