/in/foo.cc: In function 'int sum(int)':
/in/foo.cc:16:17: error: invalid types 'int[int]' for array subscript
      if(ans[a[k]] !=1){
                 ^
/in/foo.cc:18:15: error: invalid types 'int[int]' for array subscript
       ans[a[k]]=1;
               ^