Compilare: user.cpp: In function ‘void tarjan(int)’: user.cpp:21:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:57:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ctc.size(); ++i) { ^ user.cpp:58:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < ctc[i].size(); ++j) ^