Compilare: user.cpp: In function ‘std::vector<int> pal::Manacher(const string&, char)’: user.cpp:25:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ext.size(); ++i) { ^ user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i + current < ext.size() && i - current >= 0 && ^ user.cpp:36:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < pal.size(); ++i) { ^ user.cpp: In member function ‘long long int pal::PalTree::Pal2()’: user.cpp:130:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < nodes.size(); ++i) { ^ user.cpp: In constructor ‘pal::PalTree::PalTree(const string&)’: user.cpp:145:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.length(); ++i) { ^