Remove duplicates from a sorted linked list

As the linked list is sorted, we can start from the beginning of the list and compare adjacent nodes. When adjacent nodes are the same, remove the second one. There's a tricky case where the node after the next node needs to be noted before the deletion.


// Remove duplicates from a sorted list
void RemoveDuplicates(struct node* head) 
{
  struct node* current = head;
  if (current == NULL) return; // do nothing if the list is empty

  // Compare current node with next node
  while(current->next!=NULL)
  {
      if (current->data == current->next->data)
      {
         struct node* nextNext = current->next->next;
         free(current->next);
         current->next = nextNext;
      }
      else
      {
         current = current->next; // only advance if no deletion
      }
   }
}