leetcode热题100——day26

21. 合并两个有序链表

将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。

AC代码

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):def mergeTwoLists(self, list1, list2):""":type list1: Optional[ListNode]:type list2: Optional[ListNode]:rtype: Optional[ListNode]"""cur = head = ListNode(0)while list1 and list2:if list1.val <= list2.val:cur.next, list1 = list1, list1.nextelse:cur.next, list2 = list2, list2.nextcur = cur.nextcur.next = list1 if list1 else list2return head.next