bool check_board(list_type const& list, std::size_t level) { for(std::size_t i = 0 ;i < level; ++i){ if((list.at(i) == list.at(level)) || (list.at(level) - list.at(i) == level - i) || (list.at(i) - list.at(level) == level - i)) return false; } return true; }
void update_board(std::size_t pos, std::size_t val) { list_.at(pos) = val; }