Compilare: user.cpp: In function ‘long long int kruskall(std::vector<int>&, std::vector<int>&, std::vector<std::pair<std::pair<int, int>, int> >&, std::vector<std::pair<std::pair<int, int>, int> >&, int, int)’: user.cpp:58:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((ama.size() < N - 1 ) &&( i < M )) { ^ user.cpp: In function ‘int main(int, const char**)’: user.cpp:90:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < ama.size(); i++) ^ user.cpp:80:22: warning: unused variable ‘j’ [-Wunused-variable] int i, x, y , cost, j; ^