public class BST> {

public Node root;        //二叉树的根节点

private class Node

{

private Key key;    //键

private Node left,right;    //指向子树的连接

public Node(Key key)

{

this.key = key;

}

}

public void insertRec(Key key)

{

root = insertRec(root,key);

}

private Node insertRec(Node x,Key key)

{

//如果key存在则结束插入

//否则以key为键值对的新节点插入到该子树中

if(x==null) return new Node(key);

int cmp = key.compareTo(x.key);

if    (cmp<0)     x.left = insertRec(x.left,key);

else if(cmp>0)     x.right = insertRec(x.right,key);

return x;

}

public Key min()

{

return min(root).key;

}

private Node min(Node x)

{

if(x.left == null) return x;

return min(x.left);

}

public void deleteMin()

{

root = deleteMin(root);

}

private Node deleteMin(Node x)

{

if(x.left == null) return x.right;

x.left = deleteMin(x.left);

return x;

}

public void delete(Key key)

{root = delete(root,key);}

private Node delete(Node x,Key key)

{

if(x==null) return null;

int cmp = key.compareTo(x.key);

if (cmp<0) x.left = delete(x.left,key);

else if(cmp>0) x.left = delete(x.right,key);

else

{

if(x.right == null) return x.left;

if(x.left == null) return x.right;

}

return x;

}

}