Compilare: user.cpp: In function ‘long long int solve(const std::vector<int>&, int)’: user.cpp:17:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i + len < v.size()) { ^ user.cpp:22:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size() - half_size; i++) ^ user.cpp:26:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size() / 2; ++i) ^ user.cpp:7:9: warning: unused variable ‘steps’ [-Wunused-variable] int steps = half_size / len; ^