+
+struct InvertedBoard {
+ signed char pos[BOARD_SIZE];
+};
+
+struct Board {
+ signed char board[BOARD_SIZE];
+ bool is_valid() const;
+ signed char hole() const;
+ InvertedBoard invert() const;
+ int distance(const Board& o) const;
+ int distance(const InvertedBoard& invo) const;
+ bool operator==(const Board& o) const;
+ bool operator!=(const Board& o) const;
+ bool operator<(const Board& o) const;
+};
+std::istream& operator>>(std::istream& is, Board& board);
+std::ostream& operator<<(std::ostream& os, const Board& board);
+
+struct Step {
+ Step(Board board, std::shared_ptr<Step> prev);
+ ~Step();
+
+ Board board;
+ std::shared_ptr<Step> prev;
+
+ std::vector<std::shared_ptr<Step>> successors(std::shared_ptr<Step> shared_this) const;
+ int length() const;
+ int cost(const InvertedBoard& invgoal) const;
+
+ static signed char adjacent[BOARD_SIZE][5];
+ static int count;
+};
+std::ostream& operator<<(std::ostream& os, const Step& step);
+
+std::shared_ptr<Step> find_path(const std::string& start, const std::string& goal, unsigned max_frontier);
+std::shared_ptr<Step> find_path(const Board& start, const Board& goal, unsigned max_frontier);