foo.cc: In function 'int main()':
foo.cc:5:2: error: 'string' was not declared in this scope
  string c[10000];
  ^~~~~~
foo.cc:5:2: note: suggested alternative: 'struct'
  string c[10000];
  ^~~~~~
  struct
foo.cc:6:2: error: 'gets' was not declared in this scope
  gets(s);
  ^~~~
foo.cc:11:4: error: 'c' was not declared in this scope
    c[j]=c[j]+s[i];
    ^
foo.cc:16:11: error: 'c' was not declared in this scope
   reverse(c[i].begin(),c[i].end());
           ^
foo.cc:16:3: error: 'reverse' was not declared in this scope
   reverse(c[i].begin(),c[i].end());
   ^~~~~~~
foo.cc:18:3: error: 'cout' was not declared in this scope
   cout<<c[i]<<" ";
   ^~~~
foo.cc:18:9: error: 'c' was not declared in this scope
   cout<<c[i]<<" ";
         ^

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。