leetcodeday94–二叉树的中序遍历

给定一个二叉树的根节点 root ，返回它的 中序 遍历。

输入：root = [1,null,2,3]
输出：[1,3,2]

# @lc app=leetcode.cn id=94 lang=python3
#
# [94] 二叉树的中序遍历
#

# @lc code=start
# 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 inorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
        nums=[]
        def inorder(root):
            if root==None:
                return 
            inorder(root.left)
            nums.append(root.val)
            inorder(root.right)
        
        inorder(root)
        return nums
# @lc code=end