Compilare: user.cpp: In function ‘void add_trie(trie*, char*)’: user.cpp:26:14: warning: NULL used in arithmetic [-Wpointer-arith] if(*s == NULL) ^ user.cpp: In function ‘int main()’: user.cpp:155:51: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d%d%d\n", &n, &k, &win, &draw); ^ user.cpp:159:32: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(str, 1, k+1, fin); ^