Compilare: main.cpp: In function 'int bfs()': main.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<a[nod].size();i++) { ~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:80:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a[nod].size();i++) { ~^~~~~~~~~~~~~~