LeetCode算法题python解法：23. Merge k Sorted Lists

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]