51. Leetcode 106. 从中序与后序遍历序列构造二叉树 (二叉树-二叉树构建)

给定两个整数数组 inorder 和 postorder ，其中 inorder 是二叉树的中序遍历， postorder 是同一棵树的后序遍历，请你构造并返回这颗 二叉树 。

 

示例 1:


输入：inorder = [9,3,15,20,7], postorder = [9,15,7,20,3]
输出：[3,9,20,null,null,15,7]
示例 2:

输入：inorder = [-1], postorder = [-1]
输出：[-1]


# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def buildTree(self, inorder: List[int], postorder: List[int]) -> TreeNode:
        if not postorder:
            return None
        root = TreeNode(postorder[-1])
        rootIndex = inorder.index(root.val)

        root.left = self.buildTree(inorder[0:rootIndex], postorder[0:rootIndex])
        root.right = self.buildTree(inorder[rootIndex+1:],postorder[rootIndex:-1])

        return root

标签：inorder,self,51,rootIndex,二叉树,root,106,postorder
来源： https://blog.csdn.net/weixin_41362649/article/details/122760658