以下代码实现了二叉树的中序遍历，输入以下二叉树，中序遍历结果是4 2 5 1 3 6。

提供的二叉树结构图（文本描述）和代码如下： 1 / \ 2 3 / \ \ 4 5 6

Python
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1class TreeNode:
2    def __init__(self, x):
3        self.val = x
4        self.left = None
5        self.right = None
Python
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1def inorder_iterative(root):,[object Object],
2stack = [],[object Object],
3curr = root,[object Object],
4while curr or stack:,[object Object],
5while curr:,[object Object],
6stack.append(curr),[object Object],
7curr = curr.left,[object Object],
8curr = stack.pop(),[object Object],
9print(curr.val, end=" "),[object Object],
10curr = curr.right,[object Object],
11```,[object Object],