设计Hash映射

摘要：该文章展示了一个简单的Java类MyHashMap，它使用链表解决哈希冲突。类中包含put、get和remove方法，用于存储、检索和删除键值对。每个桶(buckets)是一个链表，键值对通过键的哈希值定位到对应的链表节点

设计Hash映射

class MyHashMap {

    class Node{
        int key;
        int value;
        Node next;
        public Node(int key, int value){
            this.key= key;
            this.value=value;
        }
    }
    private Node [] buckets;
    int size;
    public MyHashMap() {
        size=0;
        buckets =new Node[16];
    }
    
    public void put(int key, int value) {
        //用key直接代表hashcode（），%bucket.length能保证不会溢出
        int index = key %buckets.length;
        Node head =buckets[index];
        //只要头节点不为空，就一种找下去
        while(head != null && head.key != key){
            head =head.next;
        }
        //找到相同key
        if(head != null ){
            head.value=value;
        //不存在这个key，用的是头插法
        }else{
            Node newnode =new Node(key,value);
            newnode.next=buckets[index];
            buckets[index] =newnode;
            size++;
        }
    }
    
    public int get(int key) {
        int index= key % buckets.length;
        Node head =buckets[index];
        while(head != null && head.key != key){
            head=head.next;
        }

        return  head == null ? -1 : head.value;
    }
    
    public void remove(int key) {
        int index= key % buckets.length;
        Node head =buckets[index];      
        //创建两个临时变量,如果只有一个临时变量，则最后不能给bucket[index]进行赋值
        Node dummy= new Node(0,0);
        Node cur=dummy;
        dummy.next=head;

        while(cur.next != null && cur.next.key != key){
            cur=cur.next;
        }     
        if(cur.next!=null && cur.next.key == key){
            cur.next=cur.next.next;
            size--;
        }   

        buckets[index] =dummy.next;

    }
 
}


/**
 * Your MyHashMap object will be instantiated and called as such:
 * MyHashMap obj = new MyHashMap();
 * obj.put(key,value);
 * int param_2 = obj.get(key);
 * obj.remove(key);
 */