Compilare: main.cpp: In function 'void FFT(std::vector<std::complex<double> >&, int)': main.cpp:15:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<=A.size();i++) if (i < rev(i,lg)) swap(A[i],A[rev(i,lg)]); ~^~~~~~~~~~ main.cpp:32:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<A.size() && inv;i++) A[i] /= sz; ~^~~~~~~~~ main.cpp: In function 'std::vector<int> mult(std::vector<int>, std::vector<int>)': main.cpp:37:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (sz < max(A.size(),B.size())) sz *= 2; ~~~^~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:42:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<A.size();i++) X[i] = {A[i], 0}; ~^~~~~~~~~ main.cpp:42:49: warning: narrowing conversion of 'A.std::vector<_Tp, _Alloc>::operator[]<int, std::allocator<int> >(((std::vector<int>::size_type)i))' from '__gnu_cxx::__alloc_traits<std::allocator<int> >::value_type {aka int}' to 'double' inside { } [-Wnarrowing] for (int i=0;i<A.size();i++) X[i] = {A[i], 0}; ^ main.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<B.size();i++) Y[i] = {B[i], 0}; ~^~~~~~~~~ main.cpp:43:49: warning: narrowing conversion of 'B.std::vector<_Tp, _Alloc>::operator[]<int, std::allocator<int> >(((std::vector<int>::size_type)i))' from '__gnu_cxx::__alloc_traits<std::allocator<int> >::value_type {aka int}' to 'double' inside { } [-Wnarrowing] for (int i=0;i<B.size();i++) Y[i] = {B[i], 0}; ^ main.cpp:50:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<C.size();i++) C[i] = Z[i].real() + 0.5; ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:73:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<c.size();i++) if (c[i]) cout << i << ' ' << c[i] << '\n'; ~^~~~~~~~~ main.cpp:57:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.in","r",stdin); ^ main.cpp:58:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.out","w",stdout); ^