package search;import java.util.Random;public class BinarySearchST<Key extends Comparable<Key> , Value> {private Key[] keys; //键private Value[] vals; //值private int N;// 当前使用容量public BinarySearchST(int capacity) {keys = (Key[]) new Comparable[capacity];vals = (Value[]) new Object[capacity];}public int size() {return N;}//根据键来查找对应值public Value get(Key key) {//找出该键在数组中的下标int pos = rank(key);//如果找到的下标在范围内并且确实是这个键，说明找到了if(pos < N && keys[pos].compareTo(key) == 0) {return vals[pos];}else return null;//否则没有找到，返回空
    }//二分法查找键的位置public int rank(Key key) {int lo = 0, hi = N - 1;//二分查找while(lo <= hi) {int mid = lo + (hi - lo) / 2;if(keys[mid].compareTo(key) > 0) {hi = mid - 1;}else if(keys[mid].compareTo(key) < 0 ) {lo = mid + 1;}else {return mid;}}//如果找不到 之前一步lo必定等于hi， 看这个数字是大于还是小于，不论怎样，lo的位置都代表如果这个数存在//它应该处于的位置return lo;}public void put(Key key, Value val) {int pos = rank(key);//先看这个键有木有//如果有只需要修改一下值就行了if(pos < N && keys[pos].compareTo(key) == 0) {vals[pos] = val;}//如果没有就新建一个键值对 插入//插入的位置正好是pos 那么pos之后的数都要后移一位//如果容量已满需要扩容for(int i=N-1; i>=pos; i--) {keys[i + 1] = keys[i];vals[i + 1] = vals[i];}//空出来的位置插入新键值对keys[pos] = key;vals[pos] = val;N++;}public void delete(Key key) {int pos = rank(key);//先看这个键有木有//如果有就删除 并且后移一位if(pos < N && keys[pos].compareTo(key) == 0) {for(int i=pos; i<N-1; i++) {keys[i] = keys[i+1];vals[i] = vals[i+1];}N--;}//如果没有就返回return;}public void show() {for(int i=0; i<N; i++) {System.out.println(keys[i].toString() + " : " + vals[i].toString());}}public static void main(String[] args) {// TODO Auto-generated method stubBinarySearchST<Integer, Integer> bs = new BinarySearchST<Integer , Integer>(20);Random r = new Random();for(int i=0; i<10; i++) {Integer t1 = new Integer(r.nextInt(1000));Integer t2 = new Integer(r.nextInt(1000));bs.put(t1, t2);}bs.show();System.out.println("*********************");bs.put(999, 999);bs.put(555, 555);bs.show();System.out.println("*********************");bs.delete(555);bs.show();}}