剑指Offer 07 重建二叉树

重建二叉树

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

# -*- 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):
        n = len(pre)
        if n == 0:
            return None
        if n == 1:
            return TreeNode(pre[0])
        root = TreeNode(pre[0])
        for i in range(len(tin)):
            if tin[i] == pre[0]:
                break
        root.left = self.reConstructBinaryTree(pre[1:i+1],tin[:i])
        root.right = self.reConstructBinaryTree(pre[i+1:],tin[i+1:])
        return root
        # write code here