public LRUCache(int _capacity)
{
this.capacity = _capacity;
//useful nodes between head and tail
this.head = new DLinkedNode(0, 0);
this.tail = new DLinkedNode(0, 0);
this.head.next = tail;
this.tail.prev = head;
}
private void insert(DLinkedNode node)
{
//insert to next of head
map.Add(node.key, node);
var headNext = head.next;
head.next = node;
node.prev = head;
headNext.prev = node;
node.next = headNext;
}
private void remove(DLinkedNode node)
{
map.Remove(node.key);
node.prev.next = node.next;
node.next.prev = node.prev;
}