题解 | #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
        return self.ReConstructBinaryTree(pre, tin)
    
    def ReConstructBinaryTree(self, pre, tin):
        if len(pre) == 0:
            return None
        if len(pre) == 1:
            ret = TreeNode(pre[0])
            return ret
        ret = TreeNode(pre[0])
        idx = tin.index(pre[0])
        ret.left = self.ReConstructBinaryTree(pre[1:idx+1], tin[0:idx])
        ret.right = self.ReConstructBinaryTree(pre[idx+1:], tin[idx+1:])
        return ret