从输入的二叉排序树中删除一个结点。通过考虑该节点分别是叶节点，或只有左子树或右子树，或左右子树全不为空的状况-From the input binary sort tree to remove a node. By considering the node is a leaf node, respectively, or only a left subtree or right subtree, or left and right subtrees whole situation is not