链表：21. 合并两个有序链表 - 力扣（LeetCode）

无脑写，有点不优雅

 1 # Definition for singly-linked list.
 2 # class ListNode(object):
 3 #     def __init__(self, val=0, next=None):
 4 #         self.val = val
 5 #         self.next = next
 6 class Solution(object):
 7     def mergeTwoLists(self, list1, list2):
 8         """
 9         :type list1: Optional[ListNode]
10         :type list2: Optional[ListNode]
11         :rtype: Optional[ListNode]
12         """
13         pA = list1
14         pB = list2
15         if list1 == None and list2 == None:
16             return None
17         if list1 == None:
18             return list2
19         if list2 == None:
20             return list1
21         if pA.val <= pB.val:
22             resNode = pA
23             pA = pA.next
24             resNode.next = None
25         else:
26             resNode = pB
27             pB = pB.next
28             resNode.next = None
29         currNode = resNode
30         while pA and pB:
31             if pA.val <= pB.val:
32                 currNode.next = pA
33                 currNode = pA
34                 pA = pA.next
35                 currNode.next = None   
36             else:
37                 currNode.next = pB
38                 currNode = pB
39                 pB = pB.next
40                 currNode.next = None
41         if pA == None:
42             currNode.next = pB
43         else:
44             currNode.next = pA
45         return resNode
46 
47 
48