def mergeTwoLists(self, l1, l2):
p2 = l2
head = None
curr = None
while p1 and p2:
node = ListNode(0)
if p1.val <= p2.val:
node.val = p1.val
p1 = p1.next
else:
node.val = p2.val
p2 = p2.next
if curr:
curr.next = node
else:
head = node
curr = node
for pointer in [p1, p2]:
while pointer:
node = ListNode(pointer.val)
if curr:
curr.next = node
else:
head = node
curr = node
pointer = pointer.next
return head
def add_two_numbers(l1, l2, c=0):
node = ListNode(0)
if l1 and l2:
v = l1.val + l2.val + c
n1, n2 = l1.next, l2.next
elif l1:
v = l1.val + c
n1, n2 = l1.next, None
elif l2:
v = l2.val + c
n1, n2 = None, l2.next
elif c:
v = c
n1, n2 = None, None
else:
return None
c = v // 10
v = v % 10
node.val = v
node.next = add_two_numbers(n1, n2, c)
return node
