Compilare: main.cpp: In member function 'void skip_list::insert_node(int)': main.cpp:386:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node*>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 386 | for (int i = 1; i < levels.size(); i++) | ~~^~~~~~~~~~~~~~~ main.cpp:402:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node*>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 402 | if (level >= levels.size()) | ~~~~~~^~~~~~~~~~~~~~~~ main.cpp: In member function 'bool skip_list::delete_node(int)': main.cpp:438:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node*>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 438 | for (int i = 0; i < levels.size(); i++) | ~~^~~~~~~~~~~~~~~