Compilare: main.cpp: In function 'trie* add_trie(trie*, char*)': main.cpp:22:15: warning: NULL used in arithmetic [-Wpointer-arith] if( *s == NULL ) ^~~~ main.cpp: In function 'void dfs(trie*)': main.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < nod->edge.size(); i++ ){ ~~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'trie* add_trie(trie*, char*)': main.cpp:27:1: warning: control reaches end of non-void function [-Wreturn-type] } ^