145.binary-tree-postorder-traversal.py

#
# @lc app=leetcode id=145 lang=python
#
# [145] Binary Tree Postorder Traversal
#

# @lc code=start
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):
    def postorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """

        res = []
        def dfs(node):

            if not node: return
    
            dfs(node.left)
            dfs(node.right)
            res.append(node.val)

        dfs(root)
        return res




        
# @lc code=end