题目
You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
Merge all the linked-lists into one sorted linked-list and return it.
解题思路
把每个链表的第一个元素已经链表的标号放到优先队列里，每次pop最小的，如果后面仍有元素就继续加入到队列里
代码
class Solution:
def mergeKLists(self, lists: List[ListNode]) -> ListNode:
q = []
for i in range(len(lists)):
if lists[i]:
heapq.heappush(q, (lists[i].val, i))
lists[i] = lists[i].next
res = ListNode()
cur = res
while q:
val, i = heapq.heappop(q)
cur.next = ListNode(val)
cur = cur.next
if lists[i]:
heapq.heappush(q, (lists[i].val, i))
lists[i] = lists[i].next
return res.next
