Just Level Order Traversal the binary tree

```
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def rightSideView(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
if not root:
return []
res, level = [], [root]
while level:
res.append([node.val for node in level])
temp = []
for node in level:
temp.append(node.left)
temp.append(node.right)
level = [node for node in temp if node]
return [x[-1] for x in res]
```