Compilare: user.cpp: In member function ‘void nrx_hash::insert_hash(int)’: user.cpp:24:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < my_hash[position].size(); i ++ ) { ^ user.cpp: In member function ‘void nrx_hash::erase_hash(int)’: user.cpp:37:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < my_hash[position].size(); i ++ ) { ^ user.cpp: In member function ‘int nrx_hash::count_hash(int)’: user.cpp:47:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < my_hash[position].size(); i ++ ) { ^ user.cpp: In function ‘int main()’: user.cpp:75:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "arbore3.in" , "r", stdin ); ^ user.cpp:76:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "arbore3.out", "w", stdout ); ^ user.cpp:78:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d %d", &N, &S ); ^ user.cpp:80:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d %d", &node, &Cost[i] ); ^