Compilare: user.cpp: In function ‘int ff(std::vector<node>, int)’: user.cpp:27:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < nodes.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:83:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < p[i].size(); ++j) { ^ user.cpp:94:64: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = res.size() - 1; i >= 0 && i > res.size() -1 - k; --i) { ^