剑指offer面试题07. 重建二叉树(递归)(切片)

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。

思路

详见链接

代码

#class TreeNode:
#	def __init__(self,x):
#		self.val = x
#		self.left = None
#		self.right = None

class Solution:
	def buildTree(self,preorder:List[int],inorder:List[int])->TreeNode:
		if len(preorder) == 0:
			return None
			
		node = TreeNode(preorder[0])
		index = inorder.index(node.val)
		left_pre = preorder[1:index+1]
		left_in = inorder[:index]
		right_pre = preorder[index+1:]
		right_in = inorder[index+1:]
		
		node.left = self.buildTree(left_pre,left_in)
		node.right = self.buildTree(right_pre,right_in)
		return node