归并有序链表--Merge Two Sorted Lists

https://oj.leetcode.com/problems/merge-two-sorted-lists/

Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

题目：合并两个已经排序的链表，并实现最终排序。

 1 # Definition for singly-linked list.
 2 # class ListNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.next = None
 6 
 7 class Solution:
 8     # @param {ListNode} l1
 9     # @param {ListNode} l2
10     # @return {ListNode}
11     def mergeTwoLists(self, l1, l2):
12         if l1==None:                    #一方为空，直接返回另一个链表，无需再用结点排序
13             return l2
14         if l2==None:
15             return l1
16         dummy=ListNode(0)               #在确定二链表都不为空后，再建立头结点为下面做准备（前后逻辑顺序）
17         tmp=dummy
18         while l1 and l2:
19             if l1.val<=l2.val:          #依次比较和更新l1和l2,遍历整个链表，值小的排在前面
20                 tmp.next=l1             #连接一个结点其实代表了整个后面依次连接的结点
21                 l1=l1.next
22                 tmp=tmp.next
23             else:
24                 tmp.next=l2
25                 l2=l2.next
26                 tmp=tmp.next
27         if l1==None:                     #当l1所在链表的结点已全部merge完，剩下的l2直接连接上
28             tmp.next=l2
29         else:
30             tmp.next=l1
31         return dummy.next

 

posted @ 2015-06-28 22:48  小榛子  阅读(145)  评论(0)    收藏  举报