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:86:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < p[i].size(); ++j) { ^ user.cpp:98:9: warning: unused variable ‘l’ [-Wunused-variable] int l = r - k + 1; ^