合并两个排序的链表后，在新构造的链表的末尾没有附加任何内容

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

def mergeTwoLists(l1, l2):
    dummy = ListNode()  # 创建一个虚拟头节点
    curr = dummy  # 当前节点指针

    while l1 and l2:
        if l1.val <= l2.val:
            curr.next = l1
            l1 = l1.next
        else:
            curr.next = l2
            l2 = l2.next
        curr = curr.next

    # 将剩余的节点连接到新链表的末尾
    curr.next = l1 if l1 else l2

    return dummy.next  # 返回合并后的链表的头节点

# 示例用法
l1 = ListNode(1)
l1.next = ListNode(3)
l1.next.next = ListNode(5)

l2 = ListNode(2)
l2.next = ListNode(4)
l2.next.next = ListNode(6)

merged = mergeTwoLists(l1, l2)

# 打印合并后的链表
while merged:
    print(merged.val)
    merged = merged.next