#includegentree tree; tree.add_root(1); tree.add_child(2, 1); tree.add_child(3, 1);
#includeThis code traverses the tree in preorder and calls the "print_node" function for each node. Package/library: GenTree is a C++ library that is not part of the STL, but is available as a third-party package/library.void print_node(const int& data) { std::cout << data << std::endl; } gentree tree; // ... create and add nodes here tree.preorder_traversal(print_node);