Partition List by pivot

ListNode *partitionList(ListNode *head, ListNode *pivot)
{
   ListNode dummy_head(INT_MAX);

   dummy_head.next = head;
   ListNode *traveler = &dummy_head;
   ListNode dummy_head_partitioned_list(INT_MAX);

   ListNode *tail_partitioned_list = &dummy_head_partitioned_list;

   while (traveler)
   {
      if (traveler->next && traveler->next->val <= pivot->val)
      {
         tail_partitioned_list->next = traveler->next;
         tail_partitioned_list = tail_partitioned_list->next;
         traveler->next = traveler->next->next;
      }
      traveler = traveler->next;
   }
   tail_partitioned_list->next = dummy_head.next;

   head = dummy_head_partitioned_list.next;
   return head;
}