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

    def add_by_order(self,value):
        """
        层序添加节点，从上到下，从左到右依次添加节点。
        :param value: 要添加的节点的值
        :return: None
        """
        queue = [self]
        while queue:
            current = queue.pop(0)
            if current.left:
                queue.append(current.left)
            else:
                current.left = Node(value)
                return
            if current.right:
                queue.append(current.right)
            else:
                current.right = Node(value)
                return

    def add_by_compare(self,value):
        """
        二叉搜索树：比根节点大的放左边，其余放右边。
        :param value:要添加的值
        :return:None
        """
        if value > self.value:
            if self.left is None:
                self.left = Node(value)
            else:
                self.left.add_by_compare(value)
        if value <= self.value:
            if self.right is None:
                self.right = Node(value)
            else:
                self.right.add_by_compare(value)

    def print_by_order(self):
        """
        层序遍历一棵树，从上到下，从左到右打印节点
        :return: 打印节点的值
        """
        queue = [self]
        while queue:
            current = queue.pop(0)
            print(current.value)
            if current.left:
                queue.append(current.left)
            if current.right:
                queue.append(current.right)

    def print_by_qianxu(self):
        """
        前序遍历。先打印根节点，再打印左树，再打印右树。
        :return:
        """
        print(self.value)
        if self.left:
            self.left.print_by_qianxu()
        if self.right:
            self.right.print_by_qianxu()

t = [11,9,12,11,10,8]
root = Node(10)
for i in t:
    root.add_by_compare(i)

root.print_by_order()
print('-------------')
root.print_by_qianxu()