Compilare: main.cpp: In function 'void add(int, char*)': main.cpp:16:11: warning: NULL used in arithmetic [-Wpointer-arith] if(*s == NULL){ ^~~~ main.cpp: In member function 'void usu::insert()': main.cpp:34:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v.size() >= k) return ; ~~~~~~~~~^~~~ main.cpp: In member function 'void usu::merge(const usu&)': main.cpp:40:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(v.size() < sz + aux.v.size() && v.size() < k) v.push_back(INF); ~~~~~~~~~^~~ main.cpp:43:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j <= aux.v.size() ; ++j){ ~~^~~~~~~~~~~~~~~ main.cpp:44:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i + j - 1 >= v.size()) break ; ~~~~~~~~~~^~~~~~~~~~~ main.cpp:49:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < aux.v.size() ; ++j) ~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:78:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cli.in", "r", stdin); ^ main.cpp:79:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cli.out", "w", stdout); ^ main.cpp:81:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ main.cpp:84:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^