705. hash set design

design-hashset

Title Description

Do not use any hash table built-in library design a hash set

Specifically, your design should include the following functions

add (value): inserts a value to the hash set.
contains (value): Returns the value of the existence of this hash collection.
remove (value): given a hash value is removed from the collection. If the hash value is not set, do nothing.

Example:

= New new MyHashSet hashSet MyHashSet ();
hashSet.add (. 1);
hashSet.add (2);
HashSet.contains (. 1); // Returns to true
HashSet.contains (. 3); // returns false (not found)
hashSet. the Add (2);
HashSet.contains (2); // return to true
hashSet.remove (2);
HashSet.contains (2); // returns false (has been deleted)

note:

All values in the range [0, 1000000] is.
The total number of operations in the range [1, 10000].
Do not use the built-in hash set library.

Code

public class MyHashSet {
	private Bucket[] myBuckets;
	int totalSize;// HashSet的最大空间
	public MyHashSet(){
//		本题哈希算法采用除留余数法；处理冲突的方法使用链地址法
		totalSize = 769;// 一般选择质数
		myBuckets = new Bucket[totalSize];
//		必须对每一个单元进行实例化，否则将会抛出空指针异常
		for(int i=0;i<totalSize;i++){
			myBuckets[i] = new Bucket();
		}
	}
	
	public void add(int key){
		int index = key % totalSize;
		myBuckets[index].insert(key);
	}
	
	public void remove(int key){
		int index = key % totalSize;
		myBuckets[index].remove(key);
	}
	
	public boolean contains(int key){
		int index = key % totalSize;
		boolean res = myBuckets[index].contains(key);
		return res;
	}
}

public class Bucket {
//	每个桶维护的其实就是一个链表
//	本可以直接用链表表示桶，但是LinkedList中某些方法无法实现程序功能，所以需要重新封装
	List<Integer> container;
	public Bucket(){
		container = new LinkedList<Integer>();
	}
	
	public void insert(int key){
//		按照示例，只有非重复的元素才被添加
		if(container.indexOf(key) == -1){
			container.add(key);
		}
	}
	
	public void remove(int key){
		int index = container.indexOf(key);
		if(index!=-1){
//			存在才能删除
			container.remove(index);
		}
	}
	
	public boolean contains(int key){
		if(container.contains(key)){
			return true;
		}
		return false;
	}
}

Performance