Compilare: user.cpp: In function ‘void topo_sort(std::vector<int>&, int)’: user.cpp:31:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < rev_gr[node].size(); ++i) { ^ user.cpp: In function ‘bool dfs(int, int)’: user.cpp:42:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < gr[node].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:78:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < res.size() - 1; ++i) { ^