Chloe Jungah Kim
Chloe Jungah Kim
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[Leetcode] 145. Binary Tree Postorder Traversal

https://leetcode.com/problems/binary-tree-postorder-traversal/
[Leetcode] 145. Binary Tree Postorder Traversal

binary tree가 하나 주어졌을 때, 해당 트리의 postorder traversal의 결과를 구하는 문제

Example 1

  • Input : root = [1,null,2,3]
  • Output : [3,2,1]

Example 2

  • Input : root = []
  • Output : []

Example 3

  • Input : root = [1]
  • Output : [1]

Note

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

class Solution:
    def postorderTraversal(self, root: TreeNode) -> List[int]:
        res = []
        def postorder(self, node: TreeNode) -> None:
            if not node :
                return          
            postorder(self, node.left)
            postorder(self, node.right)
            res.append(node.val)
        postorder(self, root)
        return res
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