0001 template <typename T> BNP<T> BinNode<T>::zag() { //逆时针旋转
0002    BNP<T> v = rc;  if (!v) return this;
0003    v->parent = parent;
0004    if (parent) (IsLChild(this) ? v->parent->lc : v->parent->rc) = v;
0005    rc = v->lc;  if (rc) rc->parent = this;
0006    v->lc = this;  parent = v;
0007    updateHeight();  v->updateHeight();  if (v->parent) v->parent->updateHeight();
0008    return v;
0009 } //zag