using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        LRUCache cache = new LRUCache(2);

        cache.Put(1, 1);

        var getValue = cache.Get(1);

        Console.WriteLine(getValue);

​

    }

}

​

public class LRUCache

{

    private int capacity;

    private Dictionary<int, LinkedListNode<KeyValuePair<int, int>>> cache;

    private LinkedList<KeyValuePair<int, int>> lruList;

​

    public LRUCache(int capacity)

    {

        this.capacity = capacity;

        this.cache = new Dictionary<int, LinkedListNode<KeyValuePair<int, int>>>(capacity);

        this.lruList = new LinkedList<KeyValuePair<int, int>>();

    }

​

    public int Get(int key)

    {

        if (cache.TryGetValue(key, out LinkedListNode<KeyValuePair<int, int>> node))

        {

            // Move the accessed node to the front of the LRU list

            lruList.Remove(node);

            lruList.AddFirst(node);

            return node.Value.Value;

        }

        return -1; // Key not found

    }

​

    public void Put(int key, int value)

    {

        if (cache.TryGetValue(key, out LinkedListNode<KeyValuePair<int, int>> node))

        {

            // Update the value and move the node to the front

            node.Value = new KeyValuePair<int, int>(key, value);

            lruList.Remove(node);

            lruList.AddFirst(node);

        }

        else

        {

            // Add a new node

            if (cache.Count >= capacity)

            {

                // Evict the least recently used item

                LinkedListNode<KeyValuePair<int, int>> lastNode = lruList.Last;

                cache.Remove(lastNode.Value.Key);

                lruList.RemoveLast();

            }

​

            LinkedListNode<KeyValuePair<int, int>> newNode = new LinkedListNode<KeyValuePair<int, int>>(new KeyValuePair<int, int>(key, value));

            lruList.AddFirst(newNode);

            cache[key] = newNode;

        }

    }

}