Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:167:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < tree[node].size(); ++ i) { ^ user.cpp: In function ‘long long int solve(std::vector<int>&, int)’: user.cpp:227:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < allNodes.size(); ++ i) { ^ user.cpp: In function ‘int main()’: user.cpp:270:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hardtask.in", "r", stdin); ^