剑指offer试题——重建二叉树

# -*- coding:utf-8 -*-
#定义了类，树节点，二叉树的节点，这里节点由三部分组成，值，左侧指针，右侧指针
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

#递归思想
class Solution:
    # 返回构造的TreeNode根节点
    def reConstructBinaryTree(self, pre, tin):
        # write code here
        if len(pre) == 0:
            return None
        if len(pre) == 1:
            return TreeNode(pre[0])
        else:
            flag = TreeNode(pre[0])
            flag.left = self.reConstructBinaryTree(pre[1:tin.index(pre[0])+1],tin[:tin.index(pre[0])])
            flag.right = self.reConstructBinaryTree(pre[tin.index(pre[0])+1:],tin[tin.index(pre[0])+1:] )
        return flag