Compilare: main.cpp: In function 'void subsetsUtil(std::vector<int>&, std::vector<std::vector<int> >&, std::vector<int>&, int)': main.cpp:13:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = index; i < A.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:61:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < res.size(); i++) { ~~^~~~~~~~~~~~ main.cpp:62:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < res[i].size(); j++) ~~^~~~~~~~~~~~~~~