我正在尝试以升序将两个链表合并为1个链表

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

def mergeTwoLists(l1: ListNode, l2: ListNode) -> ListNode:
    dummy = ListNode(0)  # 创建结果链表的头部
    curr = dummy  # 当前结果链表的指针

    while l1 and l2:  # 迭代直到两个链表都遍历完
        if l1.val < l2.val:
            curr.next = l1
            l1 = l1.next
        else:
            curr.next = l2
            l2 = l2.next
        curr = curr.next

    # 将剩余的链表连接到结果链表的末尾
    curr.next = l1 if l1 else l2

    return dummy.next  # 返回结果链表的头部

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

def mergeTwoLists(l1: ListNode, l2: ListNode) -> ListNode:
    if not l1:
        return l2
    if not l2:
        return l1
    
    if l1.val < l2.val:
        l1.next = mergeTwoLists(l1.next, l2)
        return l1
    else:
        l2.next = mergeTwoLists(l1, l2.next)
        return l2