Compilare: main.cpp: In member function 'Node* Trie::insert_(char*, Node*)': main.cpp:58:16: warning: NULL used in arithmetic [-Wpointer-arith] 58 | if(s[0] == NULL) | ^~~~ main.cpp: In member function 'Node* Trie::erase_(char*, Node*)': main.cpp:79:16: warning: NULL used in arithmetic [-Wpointer-arith] 79 | if(s[0] == NULL) | ^~~~ main.cpp: In member function 'int Trie::query_prefix_(char*, Node*)': main.cpp:98:16: warning: NULL used in arithmetic [-Wpointer-arith] 98 | if(s[0] == NULL || node == NULL) | ^~~~ main.cpp: In member function 'int Trie::query_cuv_(char*, Node*)': main.cpp:113:21: warning: NULL used in arithmetic [-Wpointer-arith] 113 | else if(s[0] == NULL) | ^~~~