Compilare: main.cpp: In function 'void add(trie*, char*)': main.cpp:18:16: warning: NULL used in arithmetic [-Wpointer-arith] 18 | if ( *s == NULL ) { | ^~~~ main.cpp: In function 'void del(trie*, char*)': main.cpp:28:16: warning: NULL used in arithmetic [-Wpointer-arith] 28 | if ( *s == NULL ) { | ^~~~ main.cpp: In function 'int cnt(trie*, char*)': main.cpp:36:16: warning: NULL used in arithmetic [-Wpointer-arith] 36 | if ( *s == NULL ) return root->aparitii; | ^~~~ main.cpp: In function 'int lcp(trie*, char*, int)': main.cpp:41:16: warning: NULL used in arithmetic [-Wpointer-arith] 41 | if ( *s == NULL ) return len; | ^~~~