二叉树创建、输出

# #-*- coding:utf-8 -*-
# # @Author:zhangy
# # @Time:2019-09-27 11:25
# # reference:https://github.com/EchoLLLiu/DataStructure/tree/master/ch04tree
#
class TreeNode:
    '''二叉搜索树节点的定义'''
    def __init__(self,val,left=None,right=None):
        self.val = val
        self.left = left
        self.right = right


class OperationTree:
    def create(self,List):
        '''二叉搜索树插入操作'''
        root = TreeNode(List[0])
        lens = len(List)
        if lens >= 2:
            root.left = self.create(List[1])
        if lens >= 3:
            root.right = self.create(List[2])
        return root

    def query(self,root,data):
        '''二叉树查找操作'''
        if root == None:
            return False
        if root.val == data:
            return True
        elif root.left:
            return self.query(root.left,data)
        elif root.right:
            return self.query(root.right,data)
    def pre_order(self,root):
        '''先序输出二叉树'''
        if root == None:
            return
        print root.val
        self.pre_order(root.left)
        self.pre_order(root.right)

    def in_order(self,root):
        '''中序输出二叉树'''
        if root == None:
            return
        self.in_order(root.left)
        print root.val
        self.in_order(root.right)

    def bac_order(self,root):
        '''后续输出二叉树'''
        if root == None:
            return
        self.bac_order(root.left)
        self.bac_order(root.right)
        print root.val

    def BFS(self,root):
        if root == None:
            return
        queue = []#保存节点
        queue.append(root)
        while queue:
            #拿出队首节点
            currentNode = queue.pop(0)
            print currentNode.val
            if currentNode.left:
                queue.append(currentNode.left)
            if currentNode.right:
                queue.append(currentNode.right)

    def DFS(self,root):
        '''深度优先'''
        if root == None:
            return
        stack = []  #用栈来保存访问节点
        stack.append(root)
        while stack:
            currentNode = stack.pop()#取后加入的
            print currentNode.val
            if currentNode.right:
                stack.append(currentNode.right)
            if currentNode.left:
                stack.append(currentNode.left)


if __name__ == '__main__':

    List1 = [1, [2, [4, [8], [9]], [5]], [3, [6], [7]]]
    op = OperationTree()
    tree1 = op.create(List1)
    print('先序打印：')
    op.pre_order(tree1)
    print('中序打印：')
    op.in_order(tree1)
    print('后序打印：')
    op.bac_order(tree1)
    print('广度优先：')
    op.BFS(tree1)
    print('深度优先：')
    op.DFS(tree1)

输出结果：

C:\Users\Administrator\Anaconda3\envs\py2\python.exe "F:/ML2/算法导论/practice/12.2 二叉树.py"
先序打印：
1
2
4
8
9
5
3
6
7
中序打印：
8
4
9
2
5
1
6
3
7
后序打印：
8
9
4
5
2
6
7
3
1
广度优先：
1
2
3
4
5
6
7
8
9
深度优先：
1
2
4
8
9
5
3
6
7

Process finished with exit code 0