foo.cc: In constructor ‘PolyLinkNode::PolyLinkNode(int, int)’:
foo.cc:8:13: warning: ‘PolyLinkNode::r’ will be initialized after [-Wreorder]
    8 |         int r;
      |             ^
foo.cc:6:23: warning:   ‘PolyLinkNode* PolyLinkNode::next’ [-Wreorder]
    6 |         PolyLinkNode* next;
      |                       ^~~~
foo.cc:10:9: warning:   when initialized here [-Wreorder]
   10 |         PolyLinkNode(int x=0,int r=0):x(x),r(r),next(NULL)
      |         ^~~~~~~~~~~~
foo.cc: In member function ‘void PolyLinkList::calculate()’:
foo.cc:43:37: error: ‘pow’ was not declared in this scope
   43 |                         s += p->x * pow(x, p->r);
      |                                     ^~~