+
+std::vector<Step*> Step::successors(std::shared_ptr<Step> shared_this) {
+ std::vector<Step*> suc;
+ signed char hole_pos = board.hole();
+ for (int i = 0; adjacent[hole_pos][i] > 0; i++) {
+ suc.emplace_back(new Step{board, shared_this});
+ std::swap(suc.back()->board.board[hole_pos], suc.back()->board.board[adjacent[hole_pos][i]]);
+ }
+ return suc;
+}
+
+std::ostream& operator<<(std::ostream& os, const Step& step) {
+ if (step.prev != nullptr) {
+ os << *step.prev;
+ signed char this_hole = step.board.hole();
+ signed char prev_hole = step.prev->board.hole();
+ os << int(step.board.board[prev_hole]) << " ";
+ switch (this_hole - prev_hole) {
+ case -1: os << "right"; break;
+ case 1: os << "left"; break;
+ case -BOARD_DIM: os << "down"; break;
+ case BOARD_DIM: os << "up"; break;
+ default: os << "somehow!"; break;
+ }
+ os << std::endl;
+ }
+ return os;
+}