Compilare: user.cpp: In function ‘void dijkstra(int)’: user.cpp:44:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[x].size() ; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:81:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < a.size() ; ++i) ^ user.cpp:88:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < b.size() ; ++i) ^ user.cpp:95:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < c.size() ; ++i) ^