Compilare: user.cpp: In function ‘Node* insert(Node*, char*)’: user.cpp:29:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (trie->children[c] == NULL) ^ user.cpp:30:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] trie->children[c] = newNode(trie); ^ user.cpp:31:35: warning: array subscript has type ‘char’ [-Wchar-subscripts] return insert(trie->children[c], s + 1); ^