ericpuwang

合并两个有序链表

https://leetcode.cn/problems/merge-two-sorted-lists/description/

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。

示例1

输入：l1 = [1,2,4], l2 = [1,3,4]
输出：[1,1,2,3,4,4]

示例2

输入：l1 = [], l2 = []
输出：[]

示例3

输入：l1 = [], l2 = [0]
输出：[0]

提示

• 两个链表的节点数目范围是[0, 50]
• -100 <= Node.val <= 100
• l1和l2均按 非递减顺序 排列

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:
        if not list1 and not list2:
            return None
        dummp_list = ListNode()
        cur = dummp_list

        while list1 and list2:
            if list1.val > list2.val:
                cur.next = ListNode(list2.val)
                list2 = list2.next
            else:
                cur.next = ListNode(list1.val)
                list1 = list1.next
            cur = cur.next

        if list1:
            cur.next = list1
        if list2:
            cur.next = list2

        return dummp_list.next