重建二叉树Python

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def reConstructBinaryTree(self, pre, tin):
        if not pre or not tin:
            return None
        root=TreeNode(pre.pop(0))
        a=tin.index(root.val)
        root.left=self.reConstructBinaryTree(pre,tin[:a])
        root.right=self.reConstructBinaryTree(pre,tin[a+1:])
        return root