/in/foo.cc: In member function 'Node* Class::Search(std::__cxx11::string, Node*)':
/in/foo.cc:35:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < node->children.size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'void Class::print(Node*, int)':
/in/foo.cc:47:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < node->children.size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'bool Class::Get_bestchoice(Node*)':
/in/foo.cc:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < node->children.size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'bool Class::solve(bool, Node*)':
/in/foo.cc:68:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0; i < n_root->children.size(); i++)
                    ~~^~~~~~~~~~~~~~~~~~~~~~~~~