重建二叉树

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回构造的TreeNode根节点
    def reConstructBinaryTree(self, pre, tin):
        # write code here
        if (not pre) or (not tin) or (len(pre) != len(tin)):
            return None
        # 去除pre的值
        root = pre[0]
        rootNode = TreeNode(root)
        position = tin.index(root)

        tinleft = tin[:position]
        tinright = tin[position+1:]

        preleft = pre[1:position+1]
        preright = pre[position+1:]

        leftNode = self.reConstructBinaryTree(preleft, tinleft)
        rightNode = self.reConstructBinaryTree(preright, tinright)

        rootNode.left = leftNode
        rootNode.right = rightNode

        return rootNode