Compilare: main.cpp: In function 'void _insert()': main.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(char i = 0; i < str.size(); ++i) { ~~^~~~~~~~~~~~ main.cpp:32:23: warning: array subscript has type 'char' [-Wchar-subscripts] if(curr->nxt[c] == 0) { ^ main.cpp:33:24: warning: array subscript has type 'char' [-Wchar-subscripts] curr->nxt[c] = new Node(); ^ main.cpp:35:27: warning: array subscript has type 'char' [-Wchar-subscripts] curr = curr->nxt[c]; ^ main.cpp: In function 'void _count(int, int)': main.cpp:48:33: warning: array subscript has type 'char' [-Wchar-subscripts] if(i <= j && curr->nxt[c]) { ^ main.cpp:49:31: warning: array subscript has type 'char' [-Wchar-subscripts] curr = curr->nxt[c]; ^ main.cpp: In function 'int main()': main.cpp:79:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < S.size(); ++i) ~~^~~~~~~~~~ main.cpp:81:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(short i = 0; i < q.size(); ++i) ~~^~~~~~~~~~