145. Binary Tree Postorder Traversal刷题笔记

问题描述 后序遍历
代码：

# 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
class Solution:
    def postorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
        result = []
        def postorder(node):
            if node:                
                postorder(node.left)
                postorder(node.right)
                result.append(node.val)
        postorder(root)
        return result

运行结果：