请问大家 为什么会报错if l1.val < l2.val:
AttributeError: 'list' object has no attribute 'val'
```python
class ListNode:
def __init__(self, val=0, nextNode=None):
self.val = val
self.next = nextNode
def mergeTwoLists(self,l1, l2):
# Check if either of the lists is null
if l1 is None:
return l2
if l2 is None:
return l1
# Choose head which is smaller of the two lists
if l1.val < l2.val:
temp = head = ListNode(l1.val)
l1 = l1.next
else:
temp = head = ListNode(l2.val)
l2 = l2.next
# Loop until any of the list becomes null
while l1 is not None and l2 is not None:
if l1.val < l2.val:
temp.next = ListNode(l1.val)
l1 = l1.next
else:
temp.next = ListNode(l2.val)
l2 = l2.next
temp = temp.next
# Add all the nodes in l1, if remaining
while l1 is not None:
temp.next = ListNode(l1.val)
l1 = l1.next
temp = temp.next
# Add all the nodes in l2, if remaining
while l2 is not None:
temp.next = ListNode(l2.val)
l2 = l2.next
temp = temp.next
return head
l1 = [1,2,3]
l2 = [2,3,4]
hh = ListNode()
hh.mergeTwoLists(l1,l2)
```
