題目描述
合并 k 個排序鏈表，返回合并后的排序鏈表昧诱。請分析和描述算法的復雜度所袁。
示例:
輸入:
[
1->4->5,
1->3->4,
2->6
]
輸出: 1->1->2->3->4->4->5->6
思路
類似歸并排序，只不過merge的時候是鏈表蜈亩，即21題懦窘，鏈表節(jié)點的合并
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def mergeKLists(self, lists: List[ListNode]) -> ListNode:
if not lists:return
n = len(lists)
return self.merge(lists, 0, n-1)
def merge(self,lists, left, right):
if left == right:
return lists[left]
mid = left + (right - left) // 2
l1 = self.merge(lists, left, mid)
l2 = self.merge(lists, mid+1, right)
return self.mergeTwoLists(l1, l2)
def mergeTwoLists(self,l1, l2):
if not l1:return l2
if not l2:return l1
if l1.val < l2.val:
l1.next = self.mergeTwoLists(l1.next, l2)
return l1
else:
l2.next = self.mergeTwoLists(l1, l2.next)
return l2
AC23
