1 public class binarytree<Value> {
 2          private Node root = null;
 3          private  class Node{
 4                private Value val;
 5                private int key;
 6                private Node left,right;
 7                private int N;   //the number of the all nodes of its child nodes and itself
 8                //private int num;//the number
 9                public Node(Value val,int key,int N){
10                    this.val = val; this.N = N;this.key = key;
11                }
12            
13        }
14 
15         public  void walk(Node x) {   //O(n) time
16             if(x!=null){
17                 walk(x.left);
18                 System.out.println(x.key);
19                 walk(x.right);
20             }
21         }
22         
23         public Value get(Node x,int key){
24             if(x == null){
25                 return null;
26             }
27             
28             if(x.key>key){
29                 return get(x.left,key);
30             }
31             else if(x.key < key){
32                 return get(x.right,key);
33             }
34             else{
35                 return x.val;
36             }
37         }
38          private Node min(Node x){
39              if(x.left == null) return x;
40              return min(x.left);
41          }
42          
43          private Node deletemin(Node x){
44          if(x.left == null){return x.right;}
45          x.left = deletemin(x.left);
46          x.N = size(x.left) + size(x.right) + 1;
47          return x;
48          }
49          
50          
51          
52          private Node delete(Node x,int key){
53              if(key < x.key) x.left = delete(x.left,key);
54               else if(key > x.key) x.right = delete(x.right,key);
55               else{
56                   if(x.left == null) return x.right;
57                   if(x.right == null) return x.left;
58                   Node t = x;
59                   x = min(t.right);
60                   x.right = deletemin(t.right);
61                   x.left = t.left;
62               }
63              x.N = size(x.left) +size(x.right)+1;
64              return x;
65              
66          }
67          
68          
69          
70          
71          private  Node put(Node x,Value val,int key){
72                if(x == null) return new Node(val,key,1);
73                if(key < x.key) x.left = put(x.left,val,key);
74                else if(key > x.key) x.right = put(x.right,val,key);
75                else x.key = key;
76                x.N = size(x.left) + size(x.right) + 1;
77                return x;
78            }
79            private  int size(Node x){
80                if(x == null){return 0;}
81                else return x.N;
82            }
83            
84           
85            
86            private Node select(Node x,int k){
87                if(x == null) return null;
88                int t = size(x.left);
89                if (t>k) return select(x.left,k);
90                else if(t<k) return select (x.right,k-t-1);
91                else return x;
92            }
93            
94          
95            
96     }