题目

解题

已经排序的两个链表 可以直接同时迭代,

from typing import *


class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next


def solution(list1: Optional[ListNode], list2: Optional[ListNode]):
    f_node=ListNode(-1)
    pre=f_node
    while list1 and list2:
        if list1.val < list2.val:
            pre.next=list1
            list1=list1.next
        else:
            pre.next=list2
            list2=list2.next
        pre=pre.next
    pre.next = list1 and list1 or list2
    return f_node.next