binary-tree-right-side-view.py

# 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: TreeNode) -> List[int]:
        if not root:
            return []
        ans = []
        level = [root]
        while level:
            ans.append(level[-1].val)
            level = [child for node in level for child in (node.left, node.right) if child]
        return ans