Leetcode146-lru-cache

Leetcode146-lru-cache

 

 

思路：https://blog.csdn.net/qq_41231926/article/details/86173740

 

  int capacity;
    int size;
    Map<Integer, ListNode> map = new HashMap<Integer, ListNode>();
    ListNode head;
    ListNode last;

    class ListNode {
        int key;
        int value;
        ListNode prev;
        ListNode next;

        public ListNode(int key, int val) {
            this.key = key;
            this.value = val;
            prev = null;
            next = null;
        }

        public int getKey() {
            return key;
        }

        public void setKey(int key) {
            this.key = key;
        }

        public int getValue() {
            return value;
        }

        public void setValue(int value) {
            this.value = value;
        }
    }

    public LRUCache(int capacity) {
        this.capacity = capacity;
    }

    public int get(int key) {

        if (map.containsKey(key)) {
            return key;
        }
        return -1;
    }

    public void put(int key, int value) {

        if (map.containsKey(key)) {

           moveNode(key, value);

        } else {

            if (size < capacity) {
                insertNode(key, value);
                size++;
            } else {
                insertNode(key, value);
                last = last.next;
            }
        }
    }

    public void insertNode(int key, int value) {
        ListNode node;
        node = new ListNode(key, value);
        node.next = head;
        head = node;
        ListNode current = last;
        while (current.next != null) {
            current = current.next;
        }
        current.next = node;
    }

    public void moveNode(int key, int value) {
        ListNode node;
        node = new ListNode(key, value);
        node.next = head;
        head = node;
        while (node.next.getKey() != key && node.next.getKey() != last.getKey()) {
            node = node.next;
        }
        node.next = node.next.next;
        ListNode current = last;
        while (current.next.getKey() != key && current.next.getKey() != last.getKey()) {
            current = current.next;
        }
        current.next = current.next.next;
    }