Compilare: main.cpp: In function 'void trie::add(trie::Trie*, int, int)': main.cpp:39:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == idx) { ~~~~~~~~~^~~~~~ main.cpp: In function 'void trie::remove(trie::Trie*, int)': main.cpp:54:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (idx == s.size()) { ~~~~^~~~~~~~~~~ main.cpp: In function 'int main(int, const char**)': main.cpp:79:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < s.size() ; ++ j) { ~~^~~~~~~~~~ main.cpp:86:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < s.size() ; ++ j) { ~~^~~~~~~~~~