[LeetCode]199.二叉树的右视图（python）

1.代码

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        result1: List[int] = []
        i = 0
        queue = deque()
        result : List[List[int]] = []
        if root==None:
            return result
        queue.append(root)
        while(queue):
            length = len(queue)
            result.append([])
            for j in range (length):
                item = queue.popleft()
                if item.left:
                    queue.append(item.left)
                if item.right:
                    queue.append(item.right)
                result[i].append(item.val)
            i=i+1
        for item in result:
            result1.append(item[len(item)-1])
        return result1

2.思路

首先用result记录层次遍历的结果（见[LeetCode]102.二叉树的层序遍历（python）-优快云博客），然后用result1记录每一层的最后一个数字。