Compilare: main.cpp: In function 'int main()': main.cpp:46:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ans.size(); i++) { ~~^~~~~~~~~~~~ main.cpp:47:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < ans[i].size(); j++) { ~~^~~~~~~~~~~~~~~ main.cpp:45:46: warning: 'N' may be used uninitialized in this function [-Wmaybe-uninitialized] vector<vector<int> > ans = makeCombi(N, P); ^ main.cpp:45:46: warning: 'P' may be used uninitialized in this function [-Wmaybe-uninitialized]