foo.cc: In function 'std::string f(std::vector<std::vector<int> >, int)':
foo.cc:49:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |         for(int i=0;i<v.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In function 'int sfv(std::string)':
foo.cc:63:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |         for(int i=0;i<s.size();i++)
      |                     ~^~~~~~~~~
foo.cc:66:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |         for(int i=k;i<s.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In function 'int sfx(std::string)':
foo.cc:74:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |         for(int i=0;i<s.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In function 'int f(std::vector<std::vector<int> >, std::vector<int>, int, int)':
foo.cc:89:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |         for(int i=0;i<si.size();i++)
      |                     ~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:108:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  108 |         for(int i=0;i<xy.size();i++)
      |                     ~^~~~~~~~~~
foo.cc:103:17: warning: unused variable 'sum' [-Wunused-variable]
  103 |         int s,e,sum=0;
      |                 ^~~
foo.cc: In function 'int sfv(std::string)':
foo.cc:66:21: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
   66 |         for(int i=k;i<s.size();i++)
      |                     ^
foo.cc: In function 'int sfx(std::string)':
foo.cc:73:20: warning: 'ke' may be used uninitialized in this function [-Wmaybe-uninitialized]
   73 |         int n=0,ks,ke;
      |                    ^~
foo.cc:73:17: warning: 'ks' may be used uninitialized in this function [-Wmaybe-uninitialized]
   73 |         int n=0,ks,ke;
      |                 ^~
foo.cc: In function 'int f(std::vector<std::vector<int> >, std::vector<int>, int, int)':
foo.cc:66:21: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
   66 |         for(int i=k;i<s.size();i++)
      |                     ^
foo.cc:62:17: note: 'k' was declared here
   62 |         int n=0,k;
      |                 ^

[Hydro](https://hydro.ac)提供评测服务