Compilare: user.cpp: In member function ‘void graph::dag_shortest_path(int, std::vector<int, std::allocator<int> >&, std::vector<int, std::allocator<int> >&)’: user.cpp:104: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:149: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:150: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:153: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:158: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result