if node.left is None and node.right is None:

if pre.left == node:

pre.left = None

else:

pre.right = None

res.append(node.value)

return

if node.left is not None:

remove(node, node.left, res)

if node.right is not None:

res = []

while root.left is not None or root.right is not None:

tmp = []

if root.left is not None:

remove(root, root.left, tmp)

if root.right is not None:

remove(root, root.right, tmp)

res.append([*tmp])

res.append([root.value])

h = Node(0)

h.next = head

cur = h

while cur.next is not None and cur.next.value != 9:

cur = cur.next

cur.value += 1

cur = cur.next

while cur is not None:

cur.value = 0

cur = cur.next

q, res = [(nums1[0] + nums2[0], 0, 0)], []

while k > 0:

a, b = heapq.heappop(q)[1:]

res.append((nums1[a], nums2[b]))

k -= 1

if a + 1 < len(nums1):

heapq.heappush(q, (nums1[a + 1] + nums2[b], a + 1, b))

if b + 1 < len(nums2):

heapq.heappush(q, (nums1[a] + nums2[b + 1], a, b + 1))