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;
};
std::istream& operator>>(std::istream& is, Board& board);
std::ostream& operator<<(std::ostream& os, const Board& board);