```
class Solution:
parm = [[]]
def order(self, node, level):
if node is None:
return
else:
if level == len(self.parm):
self.parm.append([])
self.parm[level].append(node.val)
self.order(node.left, level+1)
self.order(node.right, level+1)
# @param root, a tree node
# @return a list of lists of integers
def levelOrderBottom(self, root):
if root is None:
return []
self.order(root, 0)
self.parm.reverse()
return self.parm
```

input：{1, 2}

local: [[2], [1]]

server: [[2], [1, 1]]