Compilare: user.cpp: In function ‘int main()’: user.cpp:48:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (act->son[B[j]] == NULL) act->son[B[j]] = new node(); ^ user.cpp:48:54: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (act->son[B[j]] == NULL) act->son[B[j]] = new node(); ^ user.cpp:49:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] act = act->son[B[j]]; ^ user.cpp:58:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] act = act->son[A[j]]; ^ user.cpp:34:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("conexiuni.in","r",stdin); ^ user.cpp:35:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("conexiuni.out","w",stdout); ^ user.cpp:37:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n%s\n%s", &n, &m, A + 1, B + 1); ^