依据：平衡二叉树的左右子树高度差不超过1

　　private boolean isBalanced = true;        public boolean isbalanced_solutions(TreeNode root) {        height(root);        return isBalanced;    }    private int height(TreeNode root) {        if(null == root) {            return 0;        }        int left = height(root.left);        int right = height(root.right);        if(Math.abs(left - right) > 1) {            isBalanced = false;        }        return 1+ Math.max(left, right);    }