leetcode199

 1 class Solution:
 2     def __init__(self):
 3         self.list = []
 4         self.result = []
 5         
 6     def levelOrder(self,level):
 7         count = len(level)
 8         while count > 0:
 9             root = level.pop(0)
10             self.list.append(root.val)
11             if root.left != None:
12                 level.append(root.left)
13             if root.right != None:
14                 level.append(root.right)
15             count -= 1
16         if len(self.list) > 0:
17             self.result.append(self.list[:])
18             self.list = []
19         if len(level) > 0:
20             self.levelOrder(level)
21             
22     def rightSideView(self, root: TreeNode) -> List[int]:
23         if root == None:
24             return self.list
25         else:
26             level = []
27             level.append(root)
28             self.levelOrder(level)
29             res = []
30             for li in self.result:
31                 res.append(li[-1])
32             return res
二叉树层次遍历，最后返回每一层的最后一个节点组成的集合。