foo.cc: In function 'void Mul(std::vector<int>&, int)':
foo.cc:32:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |         for(int i=0; i<v.size(); i++)
      |                      ~^~~~~~~~~
foo.cc: In function 'void Mul(std::vector<int>&, std::vector<int>&, std::vector<int>&)':
foo.cc:44:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         for(int i=0; i<x1.size(); i++)
      |                      ~^~~~~~~~~~
foo.cc:45:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |                 for(int j=0; j<x2.size(); j++)
      |                              ~^~~~~~~~~~
foo.cc:48:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |         for(int i=0; i<x3.size(); i++)
      |                      ~^~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务