Construct Binary Tree from Inorder and Postorder Traversal

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

class Solution:
    # @param {integer[]} inorder
    # @param {integer[]} postorder
    # @return {TreeNode}
    '''
    def buildTree(self, inorder, postorder):
        if not inorder or not postorder:
            return None
        root=TreeNode(postorder.pop())
        i=inorder.index(root.val)
        root.right=self.buildTree(inorder[i+1:],postorder)
        root.left=self.buildTree(inorder[:i],postorder)
        return root
    '''