0001 template <typename T> BNP<T> clone(BNP<T> p, BNP<T> t) { //深复制
0002    if (!t) return nullptr;
0003    BNP<T> x = new BinNode<T>(t->data, p, nullptr, nullptr, t->height, t->color); //先序
0004    x->lc = clone(x, t->lc);  x->rc = clone(x, t->rc);  return x; //由t复制出x
0005 } //clone: p ~ Parent;  t ~ source Tree
0006 template <typename T> BinTree<T>::BinTree(BNP<T> t) //复制子树
0007    { _root = clone<T>(nullptr, t);  _size = t->size(); }
0008 template <typename T> BinTree<T>::BinTree(const BinTree<T>& t) //复制全树
0009    { _root = clone<T>(nullptr, t._root);  _size = t.size(); }
0010 template <typename T> BinTree<T>& BinTree<T>::operator=(const BinTree<T>& t) { //赋值
0011    if (_root != t._root)
0012       { remove(_root);  _root = clone<T>(nullptr, t._root);  _size = t.size(); }
0013    return *this;
0014 } //operator=