lru

class LRUCache {
    //自建一个类
    class DNode{
        int k;
        int v;
        DNode pre;
        DNode next;
        public DNode(){};
        public DNode(int kk,int vv){k = kk;v = vv;};
    }
    //自己的属性
    private int size;
    private int capacity;
    private DNode head,tail;
    private HashMap<Integer,DNode> map = new HashMap<>();
    public LRUCache(int capacity) {
        this.size = 0;
        this.capacity = capacity;
        head = new DNode();
        tail = new DNode();
        head.next = tail;
        tail.pre = head;
    }
    
    public int get(int key) {
       DNode c = map.get(key);
       if(c == null) return -1;
       // 把原来的删除 
       c.pre.next = c.next;
       c.next.pre = c.pre;
       // 重新插入 和head产生关联
       DNode og =  head.next ;
       head.next = c;
       c.pre = head ; 
       c.next = og;
       og.pre = c;
       return c.v;
    }
    
    public void put(int key, int value) {
        //分两种情况 有或者没有
        DNode c = map.get(key);
        if(c == null){
            //新建 插到头节点去
            DNode newnode = new DNode(key,value);
            map.put(key,newnode);
            size++;
            DNode og =  head.next ;
            head.next = newnode;
            newnode.pre = head ; 
            newnode.next = og;
            og.pre = newnode;

            if(size > capacity){
                //删除尾节点
                DNode bye = tail.pre;
                bye.pre.next = bye.next;
                bye.next.pre = bye.pre;
                //从map移除
                map.remove(bye.k);
                //size--
                size--;
            }
        }else{
            
            c.v = value;
            //还是要remove啊 好累我草
            c.next.pre = c.pre;
            c.pre.next = c.next;
            // 重新插入 和head产生关联
            DNode og =  head.next ;
            head.next = c;
            c.pre = head ; 
            c.next = og;
            og.pre = c;

            
        }
    }
}