按凹入表形式横向打印二叉树结构，即二叉树的根在屏幕的最左边，二叉树的左子数在屏幕的下边，二叉树的右子数在屏幕的上边。-By indentations in the form of a horizontal print binary tree structure, that is the root of binary tree on the screen the most left, the left sub-tree the number of the screen below, the right sub-tree a few of the top of the screen.