【Leetcode_总结】199. 二叉树的右视图 - python

Q:

给定一棵二叉树，想象自己站在它的右侧，按照从顶部到底部的顺序，返回从右侧所能看到的节点值。

示例:

输入: [1,2,3,null,5,null,4]
输出: [1, 3, 4]
解释:

   1            <---
 /   \
2     3         <---
 \     \
  5     4       <---

链接：https://leetcode-cn.com/problems/binary-tree-right-side-view/description/

思路：对二叉树进行层次遍历，返回每一个层次的最后一个节点即可

代码：

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def rightSideView(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        res = []
        que = [root]
        if root == None:
            return res
        while que:
            tempList = []
            for i in range(len(que)):
                node = que.pop(0)
                tempList.append(node.val)
                if node.left:
                    que.append(node.left)
                if node.right:
                    que.append(node.right)
            res.append(tempList)
        result = []
        for r in res:
            result.append(r[-1])
        return result