【leetcode】23. Merge k Sorted Lists

题目如下：

解题思路：用最小堆，优先级队列都可以。我尝试了先把所有node的val都取出来，然后排序，最后组成新的链表，没想到也能被AC。

代码如下：

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def mergeKLists(self, lists):
        """
        :type lists: List[ListNode]
        :rtype: ListNode
        """
        vl = []
        for i in lists:
            while i != None:
                vl.append(i.val)
                i = i.next
        vl.sort()
        head = None
        current = None
        for i in vl:
            ln = ListNode(i)
            if head == None:
                head = ln
                current = head
            else:
                current.next = ln
                current = current.next
        return head