参考解析
# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution:def buildTree(self, preorder: List[int], inorder: List[int]) -> TreeNode:if not preorder or not inorder:returnroot = TreeNode(preorder[0])index = inorder.index(preorder[0])root.left = self.buildTree(preorder[1:index+1], inorder[:index])root.right = self.buildTree(preorder[index+1:], inorder[index+1:])return root
