在C ++中使用气泡排序对链接列表进行排序

Question

I have been trying to bubble sort a doubly linked list using swap function. My question is does the swap function swap the pointer, and not just the data? My code shows me it only swap the data but not the pointers. Is there any way to efficiently to swap the pointers on the linked list? Please show me the code as I am very inexperienced in coding and I do not understand other codes in other answer.

void sortPoly(PolyNode* a)
{
  PolyNode* head =a;
  PolyNode* current = head;
  PolyNode* current_next = current->next;


  int len =Polylength(current);

  if(len ==1 || len ==0)
   {
      return;
   }

for(int i =0; i < len; i++)
{
    for (int j =0; j< len -i; j++)
    {
        int sum = current->expx + current->expy;
        cout << "sum=" << sum << endl;
        int next_sum = current_next->expx + current_next->expy;
         cout << "\t nextsum=" << next_sum << endl;

        if( sum < next_sum)
        {
            cout << "current=" << current->coef << "expx = " << current->expx << "expy=" << current->expy << endl;
            cout << "current_next=" << current_next->coef << "expx = " << current_next->expx << "expy=" << current_next->expy << endl;

            std:: swap(current, current_next);
            cout << endl;
            cout << "swapped" << endl;

            cout << "current=" << current->coef << "expx = " <<    current->expx << "expy=" << current->expy << endl;
            cout << "current_next=" << current_next->coef << "expx = " << current_next->expx << "expy=" << current_next->expy << endl;

           cout << "current=" << current->coef << "expx = " << current->expx << "expy=" << current->expy << endl;
           cout << "current_next=" << current_next->coef << "expx = " << current_next->expx << "expy=" << current_next->expy << endl;

        current = current->next;

        current_next = current->next->next;
        cout << "current=" << current->coef << "expx = " << current->expx << "expy=" << current->expy << endl;
        cout << "current_next=" << current_next->coef << "expx = " << current_next->expx << "expy=" << current_next->expy << endl;
    }
   }

 }

This is my struct:

    struct PolyNode
    {
      int coef;
      int expx;
      int expy;
      PolyNode* prev;
      PolyNode* next;
     };

Please find following my response on Mac terminal.

Answer 1

I think you probably have problems in swap function. I dont think std::swap can swap also prev and next reference. to be sure, you can implement your own swap. I would do this with this function.

void swap(PolyNode* node1, PolyNode* node2){
PolyNode* prev = node1->prev;
PolyNode* next = node2->next;
if (prev)
    prev->next = node2;
if (next)
    next->prev = node1;

node1->next = next;
node1->prev = node2;

node2->prev = prev;
node2->next = node1;
}

btw, you have to move iteration out of if.

current = current->next;
current_next = current->next->next;

part has to be out of if