Compilare: user.cpp: In function ‘int main()’: user.cpp:74:51: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen((file_input + ".in").c_str(), "r", stdin); ^ user.cpp:75:53: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen((file_input + ".out").c_str(), "w", stdout); ^ user.cpp:97:22: warning: ‘d’ may be used uninitialized in this function [-Wmaybe-uninitialized] graph[i][j] = d; ^