编写一个程序实现二叉树的先序遍历、中序遍历和后序遍历的递归算法的完整代码

好的，以下为二叉树先序、中序、后序遍历的递归算法完整代码：

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

class BinarySearchTree:
    def __init__(self):
        self.root = None

    def insert(self, val):
        node = Node(val)
        if self.root is None:
            self.root = node
        else:
            curr = self.root
            while True:
                if val < curr.val:
                    if curr.left is None:
                        curr.left = node
                        break
                    else:
                        curr = curr.left
                elif val > curr.val:
                    if curr.right is None:
                        curr.right = node
                        break
                    else:
                        curr = curr.right
    
    def preorder(self, node):
        if node is not None:
            print(node.val, end=' ')
            self.preorder(node.left)
            self.preorder(node.right)
    
    def inorder(self, node):
        if node is not None:
            self.inorder(node.left)
            print(node.val, end=' ')
            self.inorder(node.right)
    
    def postorder(self, node):
        if node is not None:
            self.postorder(node.left)
            self.postorder(node.right)
            print(node.val, end=' ')

以上代码中，Node 类是二叉树节点的定义，BinarySearchTree 类是二叉搜索树的定义。insert 方法是插入节点的操作，preorder、inorder、postorder 方法是分别进行先序、中序、后序遍历的递归算法的实现。

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