Compilare: main.cpp: In function 'bool spfa()': main.cpp:55:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Edge>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 55 | for(int i = 0; i < adj[u].size(); ++i) { | ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:126:10: warning: variable 'first' set but not used [-Wunused-but-set-variable] 126 | bool first = true; | ^~~~~