706. hash map design

Title Description

Hash map design
does not use any hash table built-in library design a hash map

Specifically, your design should include the following functions

put (key, value): inserted into the hash map (key, value) value pairs. If the key corresponding to the value already exists, this value is updated.
get (key): returns the value corresponding to the given key, and if the map does not contain this key, returns -1.
remove (key): If there is this key mapping, delete this value pairs.

Example:

HashMap '= new new MyHashMap MyHashMap ();
hashMap.put (. 1,. 1);
hashMap.put (2, 2);
HashMap.get (. 1); // returns. 1
HashMap.get (. 3); // returns -1 ( not found)
hashMap.put (2, 1); // update the existing value
hashMap.get (2); // returns 1
hashMap.remove (2); // delete key data for the 2
hashMap.get (2 ); // returns -1 (not found)

note:

All values in the range [1 1000000] is.
The total number of operations in the range [1, 10000].
Do not use the built-in hash library.

Code

package pid706;

import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;

class MyHashMap {
	private int key_space;
	private List<Bucket> hash_table;
	
	public MyHashMap(){
		this.key_space = 2069;
		this.hash_table = new ArrayList<Bucket>();
		for(int i=0;i<this.key_space;i++){
			this.hash_table.add(new Bucket());
		}
	}
	
	public void put(int key,int value){
		int hash_key = key % this.key_space;
		this.hash_table.get(hash_key).update(key,value);
		// update是Bucket类中的方法
	}
	
	public int get(int key){
		int hash_key = key % this.key_space;
		return this.hash_table.get(hash_key).get(key);
		// get是Bucket类中的方法
	}
	
	public void remove(int key){
		int hash_key = key % this.key_space;
		this.hash_table.get(hash_key).remove(key);
		// remove是Bucket类中的方法
	}
}

class Bucket{
	// 一个桶对象中存放多个映射对
	private List<Pair<Integer,Integer>> bucket;
	
	public Bucket(){
		this.bucket = new LinkedList<Pair<Integer,Integer>>();
		
	}
	
	public Integer get(Integer key){
		for(Pair<Integer,Integer> pair : this.bucket){
			if(pair.first.equals(key)){
				return pair.second;
			}
		}
		return -1;
	}
	
	public void update(Integer key,Integer value){
		for(Pair<Integer,Integer> pair : this.bucket){
			if(pair.first.equals(key)){
				// key存在：更新
				pair.second = value;
				return;
			}
		}
		// key不存在：创建
		this.bucket.add(new Pair<Integer,Integer>(key,value));
	}
	
	public void remove(Integer key){
		for(Pair<Integer,Integer> pair : this.bucket){
			if(pair.first.equals(key)){
				this.bucket.remove(pair);// remove(Object o)方法
				break;
			}
		}
	}
}

class Pair<U,V>{
	public U first;
	public V second;
	
	public Pair(U first,V second){
		this.first = first;
		this.second = second;
	}
}