有序二叉树遍历(使用Python)

def pre_order_traversal(node):
    if node is None:
        return
    print(node.val)  # 访问节点的值
    pre_order_traversal(node.left)  # 递归遍历左子树
    pre_order_traversal(node.right)  # 递归遍历右子树

def in_order_traversal(node):
    if node is None:
        return
    in_order_traversal(node.left)  # 递归遍历左子树
    print(node.val)  # 访问节点的值
    in_order_traversal(node.right)  # 递归遍历右子树

def post_order_traversal(node):
    if node is None:
        return
    post_order_traversal(node.left)  # 递归遍历左子树
    post_order_traversal(node.right)  # 递归遍历右子树
    print(node.val)  # 访问节点的值