（1）根据给定二叉树的先序遍历和中序遍历结果，构造出该二叉树； （2）给出该二叉树的后序遍历结果； （3）判定该二叉树是否为平衡二叉树； -(1) According to the given binary tree preorder traversal and inorder traversal a result, constructed out of the binary tree (2) given in the post-order traversal of the bin