Compilare: user.cpp: In function ‘std::vector<int> solve(std::vector<int>&, std::vector<int>&)’: user.cpp:12:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=v1.size();i++) ^ user.cpp:17:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=v2.size();i++) ^ user.cpp:22:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=v1.size();i++) ^ user.cpp:23:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<=v2.size();j++) ^ user.cpp: In function ‘void dfs(int)’: user.cpp:53:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v[nod].size();i++) ^ user.cpp:55:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<aux.size();i++) din[nod].push_back(aux[i]); ^ user.cpp: In function ‘int main()’: user.cpp:60:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("purification.in", "r", stdin); ^ user.cpp:61:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("purification.out", "w", stdout); ^ user.cpp:63:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:64:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=0;i<n;i++) scanf("%d",&w[i]); ^ user.cpp:67:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^