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65 lines
1.4 KiB
Plaintext
65 lines
1.4 KiB
Plaintext
---
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title: '199. Binary Tree Right Side View'
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description: Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom
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sidebar:
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label: 'Binary Tree Right Side View'
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badge: 'Medium'
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---
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<Badge variant="accent">Tree BFS</Badge>
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### Example 1:
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- Input: `root = [1,2,3,null,5,null,4]`
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- Output: `[1,3,4]`
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### Example 2:
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- Input: `root = [1,2,3,4,null,null,null,5]`
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- Output: `[1,3,4,5]`
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### Example 3:
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- Input: `root = [1,null,3]`
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- Output: `[1,3]`
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### Example 4:
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- Input: `root = []`
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- Output: `[]`
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### Constraints:
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- The number of nodes in the tree is in the range [0, 100].
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- `-100 <= Node.val <= 100`
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## Solution
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```py
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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from collections import deque
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class Solution:
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def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
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res = []
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q = deque([root])
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while q:
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rightSide = None
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qLen = len(q)
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for i in range(qLen):
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node = q.popleft()
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if node:
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rightSide = node
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q.append(node.left)
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q.append(node.right)
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if rightSide:
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res.append(rightSide.val)
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return res
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```
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