Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.

Example:

Input:[  1->4->5,  1->3->4,  2->6]Output: 1->1->2->3->4->4->5->6 题目大意就是给定多个已经排序的链表合并成一个排序的链表，我这里是将多个链表的值遍历添加到一个链表中，然后重新组织链表。复杂多比较高 代码如下：

class Solution:    def mergeKLists(self, lists):        if lists == []:            return None        link = []        for i in lists:            while i != None:                link.append(i.val)                if i.next == None:                    break                i = i.next        link = sorted(link)        print(link)        if len(link) == 0:            return None        out = [ListNode(link[0])]        for i in range(1, len(link)):            out.append(ListNode(link[i]))            out[i - 1].next = out[i]        out.append(ListNode(link[-1]))        return out[0]