Skeleton for LRU cache

lru.js

/**

Design and implement a Least Recently Used (LRU) cache. It should support the following operations: get and put.

 - get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.

 - put(key, value) - Set or insert the value if the key is not already present. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item.

The cache is always initialized with a positive capacity.

Example:

LRUCache cache = new LRUCache(2);

cache.put(1, 1);
cache.put(2, 2);
cache.get(1);       // returns 1
cache.put(3, 3);    // evicts key 2
cache.get(2);       // returns -1 (not found)
cache.put(4, 4);    // evicts key 1
cache.get(1);       // returns -1 (not found)
cache.get(3);       // returns 3
cache.get(4);       // returns 4

*/

class LRUCache {
  /**
   * @param {number} capacity
   */
  constructor(capacity) {

  }

  /**
   * @param {number} key
   * @return {number}
   */
  get(key) {

  }

  /**
   * @param {number} key
   * @param {number} value
   * @return {void}
   */
  put(key, value) {

  }
}