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.
Example 1:
1 <=
/ \
2 3 <=
\ \
5 4 <=
Input: root = [1,2,3,null,5,null,4]
Output: [1,3,4]
Example 2:
Input: root = [1,null,3]
Output: [1,3]
Example 3:
Input: root = []
Output: []
Constraints:
- The number of nodes in the tree is in the range
[0, 100].
-100 <= Node.val <= 100
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# 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
from collections import deque
class Solution:
def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
if not root:
return []
q = deque([root])
res = []
while q:
res.append(q[-1].val)
size = len(q)
for i in range(size):
node = q.popleft()
if node.left:
q.append(node.left)
if node.right:
q.append(node.right)
return res
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