Leetcode: Construct Binary Tree from Inorder and Postorder Traversal @Python

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    # @param inorder, a list of integers
    # @param postorder, a list of integers
    # @return a tree node
    def buildTree(self, inorder, postorder):
        if not inorder: return None
        root=TreeNode(postorder[-1])
        rootidx=inorder.index(postorder[-1])
        root.left=self.buildTree(inorder[:rootidx],postorder[:rootidx])
        root.right=self.buildTree(inorder[1+rootidx:],postorder[rootidx:-1])
        return root