leetcode 23.合并K个排序链表(python3) 148ms

题目描述:

合并 k 个排序链表,返回合并后的排序链表。请分析和描述算法的复杂度。

示例:

输入:
[
1->4->5,
1->3->4,
2->6
]
输出: 1->1->2->3->4->4->5->6

解题思路:
思路借鉴:https://leetcode-cn.com/problems/merge-k-sorted-lists/solution/leetcode-23-he-bing-kge-pai-xu-lian-biao-by-powcai/

# 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)
        output = self.merge(lists, 0, n-1)
        return output
    def merge(self, lists: List[ListNode], head: int, tail: int) -> ListNode:
        if head == tail:
            return lists[head]
        mid = head + (tail - head) // 2
        first_list = self.merge(lists, head, mid)
        second_list = self.merge(lists, mid + 1, tail)
        return self.merge_two_list(first_list, second_list)
    def merge_two_list(self, first_list, second_list):
        if not first_list:
            return second_list
        if not second_list:
            return first_list
        if first_list.val <= second_list.val:
            first_list.next = self.merge_two_list(first_list.next, second_list)
            return first_list
        else:
            second_list.next = self.merge_two_list(first_list, second_list.next)
            return second_list

算法性能:
在这里插入图片描述

你可能感兴趣的:(leetcode,leetcode,python,链表)