foo.cc: In function 'std::vector<int> mul(std::vector<int>&, LL)':
foo.cc:11:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<A.size()||t;i++)
                 ~^~~~~~~~~
foo.cc:13:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(i<A.size())t+=A[i]*b;
            ~^~~~~~~~~
foo.cc: In function 'std::vector<int> sub(std::vector<int>&, std::vector<int>&)':
foo.cc:23:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0, t = 0; i < A.size(); i ++ )
                            ~~^~~~~~~~~~
foo.cc:26:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (i < B.size()) t -= B[i];
             ~~^~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务