Compilare: main.cpp: In function 'int lcp(std::__cxx11::string, std::__cxx11::string)': main.cpp:10:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (idx < a.size () && idx < b.size () && a[idx] == b[idx]) ~~~~^~~~~~~~~~~ main.cpp:10:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (idx < a.size () && idx < b.size () && a[idx] == b[idx]) ~~~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:15:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dictree.in", "r", stdin); ^ main.cpp:16:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dictree.out", "w", stdout); ^