二叉树中序非递归遍历代码

在二叉树的非递归中序遍历中，通常会利用栈数据结构来实现。下面是使用Python的代码示例：

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def inorder_traversal(root):
    if root is None:
        return []

    stack, output = [], []
    current = root

    while True:
        # 如果当前节点不为空，压入栈并移动到左子树
        while current is not None:
            stack.append(current)
            current = current.left
        
        # 如果栈不为空，弹出顶部节点，并添加其值到结果中，然后移到右子树
        if stack:
            current = stack.pop()
            output.append(current.val)
            current = current.right
            
        # 当前节点和所有子节点都访问完，说明遍历结束
        else:
            break
            
    return output

# 示例：
#      1
#     / \
#    2   3
#   / \  
#  4   5
root = TreeNode(1, TreeNode(2, TreeNode(4), TreeNode(5)), TreeNode(3))
print(inorder_traversal(root))  # 输出：[4, 2, 5, 1, 3]