Compilare: user.cpp: In function ‘void read()’: user.cpp:57:56: warning: format ‘%d’ expects argument of type ‘int*’, but argument 2 has type ‘ll* {aka long long int*}’ [-Wformat=] for (int i = 0; i < n; ++i) scanf("%d", &nodes[i].freq), nodes[i].l = nodes[i].r = -1; ^ user.cpp:54:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.in", "r", stdin); ^ user.cpp:56:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:57:87: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (int i = 0; i < n; ++i) scanf("%d", &nodes[i].freq), nodes[i].l = nodes[i].r = -1; ^ user.cpp: In function ‘void write()’: user.cpp:74:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.out", "w", stdout); ^