Method LRUCache

java/Linked Lists/LRUCache.java:20–30

(int capacity)

    public DoublyLinkedListNode head;
    public DoublyLinkedListNode tail;
    public LRUCache(int capacity) {
        this.capacity = capacity;
        // A hash map that maps keys to nodes.
        cache = new HashMap<>();
        // Initialize the head and tail dummy nodes and connect them to
        // each other to establish a basic two-node doubly linked list.
        head = new DoublyLinkedListNode(-1, -1);
        tail = new DoublyLinkedListNode(-1, -1);
        head.next = tail;
        tail.prev = head;
    }

    public int get(int key) {
        if (!cache.containsKey(key)) {