Compilare: main.cpp: In function 'void ins(trie*, char*)': main.cpp:22:14: warning: NULL used in arithmetic [-Wpointer-arith] 22 | if(*s == NULL) { | ^~~~ main.cpp: In function 'int del(trie*, char*)': main.cpp:34:14: warning: NULL used in arithmetic [-Wpointer-arith] 34 | if(*s == NULL) | ^~~~ main.cpp: In function 'int query(trie*, char*)': main.cpp:49:14: warning: NULL used in arithmetic [-Wpointer-arith] 49 | if(*s == NULL) | ^~~~ main.cpp: In function 'int prefix(trie*, char*, int)': main.cpp:58:14: warning: NULL used in arithmetic [-Wpointer-arith] 58 | if(*s == NULL || !nod->fiu[NR]) | ^~~~