重建二叉树
题目描述
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。
输入
[1,2,3,4,5,6,7],[3,2,4,1,6,5,7]
输出
{1,2,5,3,4,6,7}
题目解析:
代码如下
# -*- 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 len(pre)==0: return None root = TreeNode(pre[0]) pos = tin.index(pre[0]) root.left = self.reConstructBinaryTree(pre[1:pos+1], tin[:pos]) root.right = self.reConstructBinaryTree(pre[pos+1:], tin[pos+1:]) return root