Merge k Sorted Lists 合并k个有序链表

1. #include
   #include
   #include
   #include
   #include
   #include
   using namespace std;
   struct ListNode
   {
   int val;
   ListNode *next;
   ListNode(int val, ListNode next = nullptr)
   {
   this->val = val;
   this->next = next;
   }
   };
   ListNode mergeTwoLists(ListNode l1, ListNode l2)
   {
   ListNode *dummy = new ListNode(-1), *cur = dummy;
   while (l1 && l2)
   {
   if (l1->val < l2->val)
   {
   cur->next = l1;
   l1->next = cur;
   }
   else
   {
   cur->next = l2;
   l2->next = cur;
   }
   cur = cur->next;
   }
   if (l1) cur->next = l1;
   if (l2) cur->next = l2;
   return dummy->next;
   }
   ListNode mergeKList(vector<ListNode> &lists)
   {
   if (lists.empty())
   {
   return nullptr;
   }
   int n = lists.size();
   while (n < 1)
   {
   int k = (n+1) / 2;
   for (int i = 0; i < n / 2; i++)
   {
   lists[i] = mergeTwoLists(lists[i], lists[i + k]);
   }
   n = k;
   }
   return lists[0];
   }
   struct cmp
   {
   bool operator()(ListNode x, ListNode y)
   {
   return x->val > y->val;
   }
   };
   ListNode mergeKList(vector<ListNode> &lists)
   {
   priority_queue<ListNode, vector<ListNode>, cmp> qcmp;
   for (ListNode *node : lists)
   {
   qcmp.push(node);
   }
   ListNode *dummy = new ListNode(-1), *cur = dummy;
   while (!qcmp.empty())
   {
   ListNode *node = qcmp.top();
   qcmp.pop();

   cur->next = node;
   cur = cur->next;
   if (cur->next) qcmp.push(cur->next);
   

   }
   return dummy->next;
   }
   int main()
   {

   system(“pause”);
   return 0;
   }